Program Dates
June 5 - 16, 2017

Organizers:

  • Joe Checkelsky (MIT)
  • Natalia Drichko (JHU)
  • Liang Fu (MIT)
  • Kyle Shen (Cornell)
  • Jun Zhu (PSU)

The QS³ is an annual summer school with the mission of training graduate students and postdocs in condensed matter, materials, and related fields for the next "quantum revolution." The aim is to provide students an interactive learning experience with both theoretical and experimental leaders in the field and a connection to new technology. The 2017 school is focused on Quantum Computing. QS³ is supported by the National Science Foundation and the Department of Energy

Interested graduate students and postdocs are encouraged to apply. Information about financial support can be found here. Please note that partial participation is strongly discouraged.

QS3 Poster

Summary Schedule

Full Schedule

 

Published in 2017
Tuesday, 23 May 2017 09:14

Lecture Materials

Steve Girvin (Yale)

Superconducting Qubits: Theory

Lecture 1 Notes

Lecture 2 Notes

Lecture 3 Notes

 

Lecture 1 Video

 

Basic Concepts in Quantum Information

Introduction to quantum noise, measurement, and amplification

Circuit QED and engineering charge-based superconducting qubits

Extending the lifetime of a quantum bit with error correction in superconducting circuits

Realization of three-qubit quantum error correction with superconducting circuits

Exploring the Quantum: Atoms, Cavities, and Photons

 

Vlad Manucharyan (Maryland)

Superconducting Qubits: Quantum Information and Simulation

Optical Atomic Clocks

Feynman Lectures- AC Circuits

Feynman Lectures- Resonance

 

Javad Shabani (CCNY)

Topological Quantum Computing: Experiment

MIT Technology Review on Quantum Computing

Non-Abelian anyons and topological quantum computation

Journal Club: Epitaxial interfaces between superconductors and semiconductors

Two-dimensional epitaxial superconductor-semiconductor heterostructures: A platform for topological superconducting networks

New directions in the pursuit of Majorana fermions in solid state systems

 

D. McClure and A. Corcoles (IBM)

Fixed Frequency Qubits and IBM Quantum Experience I

Getting started with QX

QX Hands‐On Activity

Quantum Fourier Transform on QX

 

J. Sage (Lincoln Labs & MIT)

Ion Traps and 3D Integration

Experimental issues in coherent quantum-state manipulation of trapped atomic ions

Quantum Computing with Ions 

 

S. Pakin (LANL)

Quantum Annealing

Lecture notes (see also references therein) 

 

W. Oliver (Lincoln Labs & MIT)

Superconducting Qubits and 3D Integration

Lecture reading

 

A. Aspuru-Guzik (Harvard)

Quantum Simulation

Simulating Chemistry Using Quantum Computers

The theory of variational hybrid quantum-classical algorithms

Towards quantum chemistry on a quantum computer

Quantum reform

A variational eigenvalue solver on a photonic quantum processor

Hardware-efficient Quantum Optimizer for Small Molecules and Quantum Magnets

 

S. Lyon (Princeton)

Spin Qubits

Lecture Notes

 

D. Weiss (PSU)

Optical Lattice Quantum Computing

Lecture Notes

 

T. McQueen (JHU)

Quantum Materials

 

J. Alicea (Caltech)

Topological Quantum Computing: Theory

Lecture Notes

Designer non-Abelian anyon platforms: from Majorana to Fibonacci

See also references from J. Shabani 

 

M. Mosca (Waterloo/Perimeter)

Impacts of Quantum Computing

 

D. Freedman (Northwestern)

Coordination Complex for Quantum Computing

Forging Solid-State Qubit Design Principles in a Molecular Furnace 

Using Supramolecular Chemistry to Build Quantum Logic Gates

 

C. Monroe (Maryland)

Trapped Ion Quantum Information

Demonstrations of small ion trap quantum computers

Experimental Comparison of Two Quantum Computing Architectures

Demonstration of a Small Programmable Quantum Computer with Atomic Qubits

 

Quantum simulations with trapped ions

Quantum Simulation of Spin Models with Trapped Ions

Non-thermalization in trapped atomic ion spin chains

 

Scaling the trapped ion quantum computer

Co-designing a Scalable Quantum Computer with Trapped Atomic Ions

 

S. Hoyer (Google)

Machine Learning

Pre-reading

MNIST For ML Beginners

Neural Networks and Deep Learning

 

N. Drichko (JHU) and J. Checkelsky (MIT)

School Summary

Lecture Notes

 

 

Published in 2017
Tuesday, 23 May 2017 09:14

Participants

Lecturers 

Jason Alicea Caltech
Alan Aspuru-Guzik Harvard
Antonio  Corcoles IBM
Danna Freedman Northwestern
Steve Girvin Yale
Steve Lyon Princeton University
Vlad Manucharyan University of Maryland
Doug McClure IBM
Tyrel McQueen Johns Hopkins University
Chris Monroe University of Maryland
Michele Mosca Perimeter
Will Oliver Lincoln Labs / MIT
Scott Pakin LANL
Jeremy Sage Lincoln Labs / MIT
Javad Shabani City College of New York
David Weiss Penn State University

 

Organizers

Joe Checkelsky MIT
Natalia  Drichko Johns Hopkins University
Liang Fu MIT
Kyle  Shen Cornell
Jun  Zhu Penn State University

 

Participants

Yilikal Ayino University of Minnesota
Stanley Breitweiser New York University
Keith Britt University of Tennessee
Henry Carfagno University of Delaware
Emanuel Casiano-Diaz University of Vermont
Huiyao Chen Cornell University
Amirhossein Davoody University of Wisconsin-Madison
Avik Dutt Columbia University
Vaibhav Dwivedi Rutgers, The State University of New Jersey
Erica Grant Oak Ridge National Laboratory/ University of Tennessee
Danielle Hamann University of Oregon
Deepti Jain Rutgers University
Yifan Jiang University of Pittsburgh
Chaitali Joshi Cornell University
Amara Katabarwa University of Georgia
Marzieh Kavand University of Utah
Dorsa Komijani Florida State University (NHMFL)
Justin Lane Michigan State University
Philippe Lewalle University of Rochester
Yandong Li  Cornell University
Jingcheng Liang Purdue University
Megan Lilly Oak Ridge National Laboratory/University of Tennessee
Xiaoxue Liu Rice University
Wen-Sen Lu Rutgers, The State University of New Jersey
Xiangyu Ma University of Delaware
Fahd Mohiyaddin Oak Ridge National Laboratory
Ian Mondragon Yale University
Shantanu Mundhada Yale University
Hryhoriy Polshyn University of Illinois at Urbana-Champaign
Michael Ratner Temple University
Jasen Scaramazza Rutgers University
Karthik Seetharam California Institute of Technology
Andrew Seredinski Duke University
Huitao Shen Massachusetts Institute of Technology
Peter Siegfried University of Colorado Boulder
Volodymyr Sivak Yale University
Maryam Souri University of Kentucky
Youngkyu Sung Massachusetts Institute of Technology
Samuel Teicher Department of Energy Sunshot Initiative
Marie-Hélène Tremblay Georgia Institute of Technology
Zhong Wan Purdue University
Joel I-Jan Wang Massachusetts Institute of Technology
Jing Xu Northern Illinois University
Jing Yang University of Rochester
Jie Zhang Rice University
Wenyuan Zhang Rutgers University
Jihang Zhu The University of Texas at Austin
Published in 2017
Tuesday, 23 May 2017 09:15

Posters

Posters for June 8, 2017

 

Yilikal Ayino       

Ferromagnetism and spin-dependent transport at a complex oxide interface    

Interfacial oxide systems have garnered a lot of attention after the discovery of a conducting interface between two insulating oxides LaAlO3 and SrTiO3. This interfacial system has been shown to have two possible ground states, superconducting or ferromagnetic. Here we show via magneto-transport measurement at low temperatures that the MBE-grown polar/non-polar NdTiO3/SrTiO3 (NTO/STO) interface hosts a ferromagnetic state. We observe a very large negative magneto-resistance ratio (MR) of up to -95 % at 150 mK.   The amplitude of the negative MR decreases with increasing temperature and acquires a positive curvature above ~ 4 K.  By modeling electron transport at the interface using spin-dependent hopping, we obtain excellent quantitative agreement with the data over more that an order of magnitude in temperature.  We find that the MR depends exponentially on the temperature (T) and magnetization (M) of the sample, following MR∝Exp[-α(M/M_s)^2/k_BT], where α characterizes the spin-dependent energy cost of hopping. The system develops superparamagnetism below ~4 K.  Above 1.5K, all the superparamagnetic moments are above their blocking temperature and hence thermally fluctuate. Below 1.5K the larger moments are blocked, leading to a hysteretic MR.  Furthermore, we show that at low temperatures time-dependent MR measurements are necessary to distinguish between magnetic effects intrinsic to the sample and extrinsic effects such as heating, which can also produce a hysteretic signal.  We conclude by discussing possible microscopic mechanisms that could lead to the formation of localized magnetic moments at the NTO/STO interface. Oxygen vacancies, dislocations or substrate impurities do not play an important role in determining the electronic properties of this system.

 

Alex Breitweiser        

ARPES Investigation of Strong Point Defects on the Surface of a Topological Insulator

Topological insulators (insulators with non-trivial band topology in the bulk) acquire unique gapless edge states when placed in an ordinary insulator (e.g. air). Because these edge states are symmetry protected, they exhibit useful properties such as ballistic transport and massless dispersion, and are resilient to even extreme local defects. Here we investigate the effect of non-magnetic defects on the surface of a topological insulator, and show numerically that defects give rise to resonant surface states which cluster around the defects. We also report on experimental efforts to find these resonant states through the use of synchrotron-based X-ray spectroscopy on defect-rich samples of bismuth selenide.

 

Keith Britt

Statistical Testing of an Adiabatic Quantum Computer's Qubit Chains      

We chain physical superconducting qubits to create a singular logical qubit, exploring how chain length influences result validity. We incorporate thermalization and annealing timing parameter variations to build statistical models predicting the expected reliability of future annealing samples. We also show a skewing or bias in relatively large qubit chains that deviate from expected uniform distributions.

 

Henry Carfagno

Toward scalable quantum photonic devices based on InAs Quantum Dots           

Quantum photonic devices promise dramatic advantages in secure communications, computing, and metrology. InAs quantum dots (QDs) have long been of interest for such applications and many required functions, such as all-optical coherent control of single spins confined in QDs, have been demonstrated. However, there are two primary roadblocks to the scalable production of single photon quantum photonic devices based on InAs QDs: poor spatial control and poor spectral control. Poor spatial control hampers the production of devices incorporating multiple QDs coupled to photonic device components. Although site-templated QDs have been grown, their optical quality tends to be very poor and thus randomly-positioned self-assembled QDs are most commonly used. Poor spectral control arises from inhomogeneous distribution of optical transition energies inherent to the self-assembly process and inhibits deterministic strong coupling of multiple QDs to either photonic device elements or external optical fields. We are developing a material platform intended to overcome both roadblocks. We aim to achieve spatial control by using a pre-patterned substrate to nucleate “tracer” QDs. The “tracer” layers of such “tracer” QDs can transfer the pattern through strain propagation that provides preferential nucleation sites for QDs in subsequent layers. Optically active QDs grown on top of these “tracer” QDs, far above the patterned substrate, can have much better optical properties. We aim to address spectral control by making our optically active element a quantum dot molecule comprised of two QDs stacked along the growth direction and embedded in a p-i-n junction. This structure allows for the local application of an electric field that can tune the indirect optical transitions of the quantum dot molecule over a range much larger than that of single QDs. We anticipate that this material platform will allow the deterministic and scalable fabrication of quantum photonic devices incorporating InAs QDs.

 

Emanuel Casiano-Diaz   

Particle partition entanglement of one dimensional spinless fermions   

We investigate the scaling of the Rényi entanglement entropies for a particle bipartition of interacting spinless fermions in one spatial dimension. In the Tomonaga-Luttinger liquid regime, we calculate the second Rényi entanglement entropy and show that the leading order finite-size scaling is equal to a universal logarithm of the system size plus a non-universal constant. Higher-order corrections decay as power-laws in the system size with exponents that depend only on the Luttinger parameter. We confirm the universality of our results by investigating the one dimensional t − V model of interacting spinless fermions via exact-diagonalization techniques. The resulting sensitivity of the particle partition entanglement to boundary conditions and statistics points to its utility in future studies of quantum liquids.

 

Huiyao Chen

Coherent Quantum Control of NV Center Using a Mechanical Resonator

With both their spins and orbitals(cryogenic temperature) strongly coupled to environmental electric, magnetic and strain field, plus long coherence time that preserves at room temperature, nitrogen vacancy(NV) centers in diamonds are promising candidates for quantum information processing and sensing. Coherent spin-phonon(strain) and orbital-strain interaction of NV centers are of great interests for their applications in force sensing at nanoscale, qubit cooling/control of optomechanical system, constructing mechanical quantum transducers in hybrid quantum system, etc. Engineeing bulk diamond as high Q mechanical resonator, and GHz frequency piezoelectric transducer as phonon source,  we explore the interplay between phonon and NV center Qubit in the quantum regime.

 

Amirhossein Davoody   

Theory of Exciton Energy Transfer in Carbon Nanotube Composites        

Carbon nanotubes (CNTs) are promising building blocks for organic photovoltaic devices, owing to their tunable band gap, mechanical and chemical stability. We study intertube excitonic energy transfer between pairs of CNTs with different orientations and band gaps. The optically bright and dark excitonic states in CNTs are calculated by solving the Bethe-Salpeter equation. We calculate the exciton transfer rates due to the direct Coulomb interactions, as well as the second-order phonon-assisted processes. We show the importance of phonons in calculating the transfer rates that match the measurements. In addition, we discuss the contribution of optically inactive excited states in the exciton transfer process, which is difficult to determine experimentally. Furthermore, we study the effects of sample inhomogeneity, impurities, and temperature on the exciton transfer rate. The inhomogeneity in the CNT sample dielectric function can increase the transfer rate by about a factor of two. We show that the exciton confinement by impurities has a detrimental effect on the transfer rate between pairs of similar CNTs. We show that the second-order phonon-assisted hopping process between bright excitonic states is as fast as the first-order one (∼ 1 ps). Moreover, second-order exciton transfer between dark and bright states, facilitated by phonons with large angular momentum, has rates comparable to bright-to-bright transfer, unlike the orders-of-magnitude disparity between the corresponding first-order rates. Therefore, dark excitonic states, which are difficult to probe with common measurement techniques, provide an efficient pathway for exciton transfer in CNT composites. This work demonstrates the importance of second-order processes for the understanding and predictive modeling of exciton transfer in CNT composites.

 

Avik Dutt

On-chip quantum and nonlinear optics in silicon nitride 

Silicon nitride (Si3N4) is a versatile platform for quantum and nonlinear optics on chip due to its high linear and nonlinear index of refraction combined with low optical losses and CMOS compatibility. This has made Si3N4 a platform of choice for generating quantum states of light on chip, such as squeezed states, as well as for performing integrated quantum interference experiments, with promising applications in continuous variable quantum information processing and quantum enhanced sensing. We have reported the generation of bright squeezed light using Si3N4 microring optical parametric oscillators above threshold.  We have shown mechanisms to tune this degree of squeezing using integrated microheaters and coupled rings. Our work has the potential to realize continuous variable EPR-type entanglement on a fully integrated silicon photonic chip, making it a scalable resource for future quantum technologies.

 

Vaibhav Dwivedi

Quantum Quench of Lieb-Liniger Hamiltonian    

 

Erica Grant

Controlling Adiabatic Quantum Computing

Adiabatic quantum computing (AQC) is a computational model that solves problems through continuous-time quantum dynamics. Per the adiabatic theorem, the quantum state can be continuously transformed under slowly evolving changes of the system Hamiltonian. An important part in designing programs for the AQC model is specifying the controls that transform this Hamiltonian from its initial to final form. We investigate the effects of different control schedules on the quantum dynamics underlying these programs and we evaluate the impact of these changes on the performance of various quantum-accelerated applications. As an example, we discuss the impact of local adiabatic evolution to use a variable rate of evolution based on the estimated size of the system energy gap. While this approach has been shown previously to realize the quadratic speedup found in Grover’s gate-based algorithm, we discuss this problem in the context of more general Hamiltonians and systems. Because local adiabatic evolution can only be applied if the shape of the energy landscape is understood, we make use of modeling and simulation of the adiabatic quantum dynamics to understand and evaluate novel control paradigms.

 

Danielle Hamann

Emergent Properties in [SnSe]m[TiSe2]n Heterostructures Prepared from Designed Precursors.              

The discovery of emergent properties has spurred Interest in monolayers and heterostructures. Emergent properties are those which exist in a monolayer or a heterostructure, but are absent in the individual bulk constituents. Emergent properties are difficult to predict, hard to control, and present challenges in understanding their origin. Preparing metastable compounds using the modulated elemental reactants method enables control of the nanoarchitecture in heterostructure compounds. This facilitates the synthesis of series of compounds with designed changes in structure, enabling the study of emergent properties as a function of the thickness of a constituent layer or layering order within a heterostructure. Several series of heterostructures within the [(SnSe)1+]m[TiSe2]n family have been synthesized and display systematic nanoarchitecture depend properties. Various diffraction techniques and high angle annular dark field scanning transmission electron microscopy were used to determine structure. The SnSe constituent structure changes significantly with thickness. Transport properties (temperature dependent Hall and resistivity data) vary systematically with m and n, with the changes reflecting both the structural changes in the heterostructures and the interaction between the constituent layers. Additional knowledge of how the layers interact is necessary to fully understand the origin of these unique properties. This understanding is required to design heterostructures with targeted properties for specific applications.

 

Deepti Jain

Quantum Anomalous Hall Effect in Magnetic Topological Insulators

The discovery of quantum Hall effect (QHE) showed great potential in the development of low-power consumption and high speed electronic devices due to dissipationless edge states. However, the requirement of extremely high magnetic fields prevented the practical realization of such devices. Naturally, the question arose whether it is possible to achieve the quantum Hall state in the absence of an external magnetic  field. Thus began the search for the quantum anomalous Hall effect (QAHE), which was predicted to exhibit quantized Hall conductance without the application of a magnetic  field. My poster provides an overview of the first experimental realization of the QAHE in magnetic topological insulators (TI) and my current work related to the topic.

 

Yifan Jiang

Development of Ferromagnetic Contacts to InSb Nanowires

The poster will be a very brief introduction of motivations, theory and experiments on ferromagnetic contacts to lnSb nanowires. Some simple preliminary results are presented.

 

Chaitali Joshi

Frequency Domain Photonic Quantum Information Processing

Frequency encoding of information has had a profound impact on classical telecommunication technologies, but remains relatively unexplored for quantum information processing (QIP). The revolutionary potential of the frequency degree of freedom of a photon lies in the fact that it enables dense encoding and processing of information in a single spatial mode. Here we present the first demonstration of the Hong-Ou-Mandel interference with optical photons in the frequency domain, and potential applications to problems such as BosonSampling. Frequency encoding is uniquely positioned to address multiple challenges facing photonic QIP due to the inherently high-dimensional nature of the spectral degree of freedom of a photon, and the highly mature fiber and integrated technologies optimized for classical applications. This demonstration of frequency domain HOM interference serves as a fundamental experimental advancement in this relatively unexplored domain, that can potentially enable massively parallel, robust, and scalable all-optical quantum information processing.

 

Amara Katabarwa

Understanding the Pauli Twirling Approximation

The success of fault-tolerant error correction is necessary for understanding the performance of potential quantum computers, but requires physical error models that can be simulated efficiently with classical computers. The Gottesmann-Knill theorem guarantees such class of such error models. Of these, the simplest is the Pauli twirling approximation (PTA), which is obtained by twirling a completely positive channel over the Pauli basis. We test PTA's accuracy at predicting a code's logical error rate by simulating the 5-qubit code circuit with decoherence and unitary gate errors. We find evidence for good agreement with exact simulation, with the PTA typically overestimating the logical error rate by a factor of 3.  Also restricting ourselves to analysis of free dynamics of qubits we show explicitly how application of PTA is equivalent to ignoring most of the quantum back action of the system and give a general argument as to why this approximation leads to low logical error rates in fault tolerant stabilizer circuits as compared to other quantum channels. We provide numerical evidence that PTA's performance in modeling noise gets worse as number of qubits increase.

 

Marzieh Kavand              

Pulsed Ferromagnetic Resonance Driven Inverse Spin-Hall Effect in Organic and Inorganic Materials

The spin-orbit coupling (SOC) strength and the spin diffusion length are crucial parameters for the applicability of a material for spintronics and measuring them accurately is therefore a crucial prerequisite for progress within this field. We have recently made progress on such measurement techniques by demonstration of pulsed inverse spin-Hall effect (ISHE) experiments for which we employed a pulsed ferromagnetic resonance (FMR) spin-pumping scheme in order to inject a pure spin current from a ferromagnetic (FM) substrate into organic semiconductor (OSEC) layers. When the FM is in resonance with pulsed microwave excitation, a strong, pure (that means charge free) spin-current is formed in the OSEC, which circumvents the impedance mismatch between the FM layer and the organic film. Because of the weak SOC in most OSECs, the inverse spin Hall effect (ISHE) that results from the spin pumping scheme is very subtle; yet with pulsed, high microwave power excitation of the FMR, strong p-ISHE signals can be measured, while, by choice of low duty cycles, measurements artifacts due to heating and other electromagnetic effects are minimized at the same time. As the magnitude of the ISHE scales linearly with the Pointing flux that drives FMR, quantitative ISHE measurements require precise control of the FMR driving field amplitude B1. This is achieved by monitoring the Rabi nutation of paramagnetic spin-probes in proximity of the device on which the ISHE is measured.

 

Dorsa Komijani

Electro-Nuclear Clock Transitions In A Ho(Iii)  Molecular Nanomagnet

An obstacle in the employment of spin qubits in quantum information processing is their short coherence time. At low temperatures, the magnetic dipolar interaction is the primary source of decoherence. The contribution from the dipolar coupling to the surrounding spins can be suppressed using atomic clock transition (CTs) [1].  CTs are referred to the transitions that are robust against the variations in the magnetic field. Here, we report pulsed electron paramagnetic resonance (EPR) studies of a Holmium Polyoxometalate, where we exploit CTs to enhance coherence time [2].  Pulsed EPR measurements were performed on crystals with two different concentrations of holmium (diluted in an isostructural diamagnetic matrix). Aside from a dramatic enhancement in the phase coherence time, we observed that at the CTs the Electron Spin Echo Envelope Modulation (ESEEM) vanishes. This further confirms that the Ho (III) spins become decoupled from the neighboring protons at CTs.  We also observed electro-nuclear clock transitions in the concentrated sample that involve coupled dynamics of the electron and nuclear spins. These transitions are formally forbidden in EPR, however, the symmetry of this molecule generates admixtures of the ground doublet through second order perturbation. Furthermore, application of a transverse magnetic field mixes the mI and mI+1 states, allowing such transitions to occur in the vicinity of avoided level crossings. Our experimental results suggest an enhancement in the coherence time at these electro-nuclear clock transitions. This is significant for applications in hybrid magnetic qubits, where manipulation of the nuclear spin is controlled by EPR pulses.

[1] G. Wolfowicz, et al., Nature Nanotechnology 8, 561 (2013).

[2] M. Shiddiq, D. Komijani, et al., Nature 531, 348 (2016)."

 

Justin Lane         

Investigating the two-dimensional conductivity of graphene using surface acoustic wave devices             

Surface acoustic waves (SAW) propagating on a piezoelectric substrate can be a sensitive probe of the dynamical conductivity of a nearby two-dimensional electron system (2DES). Enhanced absorption of acoustic energy can occur when the wavelength, or frequency, of the SAW become comparable to some other length, or time, scale within the 2DES.  Utilizing a flip-chip SAW device, we implement SAW measurements of the frequency and wavevector dependent conductivity of both chemical vapor deposition grown and exfoliated graphene. Our flip-chip architecture allows us to measure graphene conductivity at low temperatures and high magnetic fields, vary the graphene carrier density in situ, and change the resonant SAW frequency by interchanging devices with different SAW transducer geometry.

 

Philippe Lewalle

Prediction and Characterization of Multiple Extremal Paths in Continuously-Monitored Qubits   

We examine optimal paths between initial and final states for diffusive quantum trajectories in continuously monitored qubits, obtained as extrema of a stochastic path integral. We demonstrate the possibility of “multipaths” in the dynamics of continuously-monitored qubit systems, wherein multiple optimal paths travel between the same pre- and post-selected states over the same time interval. Optimal paths are expressed as solutions to a Hamiltonian dynamical system. The onset of multipaths may be determined by analyzing the evolution of a Lagrangian manifold in this phase space, and is mathematically analogous to the formation of caustics in ray optics or semiclassical physics. We apply our methods in two systems: a qubit with two non-commuting observables measured simultaneously, and a Rabi-driven qubit monitored through its fluorescence signal [arXiv:1612.03189]. We demonstrate that both systems contain multipaths generated by paths with different “winding numbers” about the Bloch sphere, and multipaths generated by catastrophes in the Lagrange manifold.

 

Yandong Li

All-Silicon Valley Hall Photonic Topological Insulator

Based on the same physical principles as the conventional condensed-matter topological insulators, Photonic Topological Insulators (PTIs) guide unidirectional electromagnetic wave, instead of electrons. The PTI-based unidirectional waveguides do not suffer from back-reflections and local impurities, and therefore can be applicable to a large integrated photonic structure. The all-silicon PTI is an analogue to the quantum valley Hall effect condensed-matter topological insulator. We demonstrate the existence of a topological edge state between two all-silicon PTIs with different valley indices, the in- and out-coupling between the PTI and the free space and a design of an optical delay line based on this PTI.

 

Posters for June 15, 2017

 

Jingcheng Liang

Charge carrier holes and Majorana fermions

Understanding Luttinger holes in low dimensions is crucial for numerous spin-dependent phenomena and nanotechnology. In particular, hole quantum wires that are proximity coupled to a superconductor is a promising system for the observation of Majorana fermions. Earlier treatments of confined Luttinger holes ignored a mutual transformation of heavy and light holes at the heteroboundaries. We derive the effective hole Hamiltonian in the ground state. The mutual transformation of holes is crucial for Zeeman and spin-orbit coupling, and results in several spin-orbit terms linear in momentum in hole quantum wires. We discuss the criterion for realizing Majorana modes in charge carrier hole systems. GaAs or InSb hole wires shall exhibit stronger topological superconducting pairing, and provide additional opportunities for its control compared to InSb electron systems.

 

Megan Lilly

Simulations of Quantum Error Correction and Fault-Tolerant Quantum Computing Systems

Quantum computing offers a fundamentally new approach to storing and processing information, but the physical encoded qubits are susceptible to noise from the surrounding environment and the externally applied gate fields. Quantum error correction offers an important method for recovering from noisy operations provided it can be implemented fault tolerantly. Fault-tolerant operations within a quantum computer must act on the encoded data while adhering to the constraints imposed by the hardware. The threshold theorem provides evidence that it is possible to achieve fault-tolerance provided the physical error rate is sufficiently low. However, these results do not account for specific physical layouts and realistic noise models. We study the influence of realistic noise and device design on the ability for different QEC codes and fault-tolerant protocols to reach threshold. We investigate various quantum error correction systems by using numerical simulation techniques based on stochastic Clifford channels and tensor networks. These mathematical representations provide efficient models for quantum simulations that can be used to quantify logical error rate.  We present a sample of simulation results of Bell state maintenance and the Steane [7,1,3] encoding and discuss future directions for research.

 

Xiaoxue Liu

Thermopower and Nernst measurements in a half-filled lowest Landau level

Recently Son presented a particle-hole symmetric (PHS) fermionic quasiparticle theory for half-filled lowest Landau level - massless Dirac composite fermions (DCF) [1],which is different from the PHS broken HLR theory [2]. Subsequently, thermoelectric transport experiments were proposed to differentiate the DCF and HLR. Motivated by this, we systematically study the electronic and thermoelectric properties of v = 1/2 and 3/2 in high-mobility GaAs/AlGaAs 2DEGs. In this poster,preliminary results will be presented.

[1] Dam Thanh Son, Phys. Rev. X 5, 031027 (2015).

[2] B. I. Halperin, P. A. Lee, and N. Read, Phys. Rev. B 47, 7312 (1993).

[3] Andrew C. Potter, Maksym Serbyn, and Ashvin Vishwanath, Phys. Rev. X 6, 031026 (2016).

 

Wen-Sen Lu

Dynamics of 1D Josephson chains in the regime of E_C << E_J ~ kT

 

Xiangyu Ma

Engineering Hole Spins in InAs/GaAs Quantum Dot and Quantum Dot Molecule using 2-D Electric Field

Self-assembled InAs/GaAs quantum dot (QDs) and quantum dot molecules (QDMs) are promising solid-state material platforms for quantum information applications. People have demonstrated that the optical and spin properties of individual QD and QDM can be fine-tuned by external electric field, either in the growth direction or in-plane direction. In order to further understand the properties of hole spin in single QD and QDM, we use tight-binding atomistic simulation to map a single hole spin state under various electric field and magnetic field conditions. We show that under a 1T Voigt geometry magnetic field, in-plane electric field can induce out-of-plane hole spin component by pushing the wave function of hole state to the edge of the QD. We also show that a 2-D electric field that has a gradient can induce mixed hole spin state in a symmetric shaped QDM. We present our design and fabrication process of a 4-electrode device, in order to apply both growth direction and in-plane direction electric field to a single QD or QDM at the same time. We also discuss some of the preliminary results of a single QD in 2-D electric field using low-temperature photoluminescence experiment.

 

Fahd Mohiyaddin

Designing Silicon Qubits with Advanced Simulation Methods

Electron and nuclear spins are strong candidates for qubits in a quantum processor due to their long coherence/relaxation times and compatibility with the microelectronics industry [1]. There are three crucial elements of a spin based quantum computer - (i) a well-defined spin qubit that can be readout and controlled in a nanostructure (ii) precise control of the exchange coupling between two spin qubits for two-qubit operations and (iii) a robust method to transport the spin qubit to different parts of the quantum computer [1, 2]. Here, we model and design several silicon nanodevices with a range of classical electrostatic and quantum simulation techniques [3], to demonstrate the above building blocks.  We first present a non-invasive spatial metrology procedure that locates donor spin qubits to a precision several thousand times smaller than current statistical techniques, for high fidelity spin readout and control [4, 5]. We then investigate a method that offers massive tunability (5 orders of magnitude) of the exchange coupling between donor electron spins (20 nm apart) [6]. For spin transport, we model donor chains [7] under realistic experimental conditions, and highlight that transport (100 nm) fidelities greater than 99.99 % are achievable across them [8]. Finally, we propose a novel technique to couple donor qubits (separated by several hundreds of nanometers) via their dipolar interaction, as well as through the photonic mode of a resonant cavity [9].  With the above, our modeling aids to estimate the required device topologies, qubit positions and electric fields – for high fidelity readout, control, exchange and transport of quantum spin information. Our results thereby provide a range of design considerations and feedback to experimentalists, who are in a global race to develop a fully scalable quantum computer.

[1] B. E. Kane. Nature 393, 133 (1998).                                                 

[2] L. C. L. Hollenberg et al. Physical Review B 74, 045311 (2006).

[3] T. S. Humble et al. Nanotechnology 27, 42, 424002 (2016).

[4] A. Laucht et al. Science Advances, 1, 3 (2015).

[5] F. A. Mohiyaddin et al. Nano Letters, 13, 1903 (2013).                    

[6] F. A. Mohiyaddin, Ph.D. thesis,  University of New South Wales (2014).

[7] M. Friesen  et al. Phys. Rev. Lett. 98, 230503 (2007).                       

[8] F. A. Mohiyaddin et al. Physical Review B, 94, 045414 (2016).

[9] G. Tosi et al. arxiV:1509.08538 (2017).

 

Shantanu Mundhada

Stabilization of a manifold of coherent states for quantum error correction.

Stabilization of quantum manifolds is at the heart of error-protected quantum information storage and manipulation. Stabilizing a manifold of four coherent states of a harmonic oscillator against energy relaxation and dephasing facilitates realization of an error corrected logical qubit. Such stabilization requires a four-photon drive and dissipation on the harmonic oscillator. In this poster, we explain a theoretical proposal to engineer such a four-photon driven-dissipative process by cascading experimentally demonstrated two-photon exchange processes.

 

Hryhoriy Polshyn

Probing and manipulating multi-vortex states in superconducting structures      

New ways to investigate and manipulate superconducting vortices are of great practical and fundamental interest. Multi-vortex states could be employed to study vortex interactions and interference effects, to braid Majorana bound states by winding vortices, and to create novel superconducting devices. We demonstrate a new mode of magnetic force microscopy ($\Phi_0$-MFM),  that enables us to induce, probe and control multi-vortex states in superconducting structures. By using a MFM tip as a source of inhomogeneous magnetic field, we can efficiently explore the configuration space of vortex states supported by the structure. $\Phi_0$-MFM enables us to map the transitions between tip-induced vortex states during a scan: at the positions of the tip, where the two lowest energy vortex configurations become degenerate, small oscillations of the tip drive transitions between these states, which causes a significant shift in the resonant frequency and dissipation of the cantilever. We show that measured patterns of vortex transitions allows us to identify these states, manipulate them, investigate their energetics and dynamics.

 

Michael Ratner

Quantum Walks and Spatial Searches on Free Groups and Networks

Quantum walks have been utilized by many quantum algorithms which provide improved performance over their classical counterparts. Quantum search algorithms, the quantum analogues of spatial search algorithms, have been studied on a wide variety of structures. We study quantum walks and searches on the Cayley graphs of finitely-generated free groups. Return properties are analyzed via Green’s functions, and quantum searches are examined.  Additionally, the stopping times and success rates of quantum searches on random networks are experimentally estimated.

 

Karthik  Seetharam

Thermalization in Driven Quantum Systems        

Periodic driving is of considerable interest due to its promising potential for engineering and control of quantum systems. In these works, we study thermalization in both open and closed driven (Floquet) systems in the presence of interactions. In the case of open systems, we analyze the steady states and show how one may control them with dissipation. In the case of closed systems, we study finite size systems and analyze the scaling behavior of heating.

 

Andrew Seredinski

Ballistic graphene Josephson junctions from the short to the long regime            

We explore the critical current (I_C) temperature scaling of ballistic Josephson junctions. Using encapsulated graphene/boron-nitride heterostructure devices, we vary device length from the short to the long junction regime. We extract the carrier-density-independent energy δE by calculating the ballistic cavity level spacing through the Fabry-Perot oscillations of the normal resistance. In the long and intermediate junction regimes, we find I_C scales as exp(-kBT/ δE) at higher temperatures. For short junctions, we find strong agreement with theoretically predicted I_C behavior. In the zero temperature limit, I_C of a long (short) junction saturates at a magnitude determined only by the product of δE (Δ) and the number of transversal modes in the junction.

 

Peter Siegfried

Anisotropic Responses in Magnetic Materials

Studies of materials’ anisotropic responses offer a convenient window into characterizing the behavior of magnetic structures. We investigated the angular dependence of electron transport properties in Mn0.9Fe0.1Si within the A-phase. We found the fully formed Skyrmion planes rotate freely with the applied field, decoupled from Fe impurities and the underlying crystalline lattice. The presence of Fe impurities only plays a minor role in the field and angle dependence, highlighting the robustness of the electrical signals resulting from these spin textures. We also studied the strain dependence of sample resistance in Cr1/3NbS2, and BaIrO3. We find highly strain dependent negative resistance changes in these ferromagnetic materials. BaIrO3 shows highly anisotropic and hysteretic strain dependence, demonstrating that its bonds and bond angles coupled with the ferromagnetic phases play a vital role in the material’s electronic properties.

 

Volodymyr Sivak

Three-wave mixing element for parametric amplifiers in circuit QED

Parametric conversion and amplification based on three-wave mixing are powerful primitives for efficient quantum operations. For superconducting qubits, such operations can be realized with a quadrupole Josephson junction element, the Josephson Ring Modulator (JRM), which behaves as a loss-less three-wave mixer. Since combining multiple quadrupole elements is a difficult task, it would be advantageous to have a pure three-wave dipole element that could be tessellated for increased power handling and/or information throughput. Here, we present a novel dipole circuit element with third-order nonlinearity, which implements three-wave mixing while minimizing harmful Kerr terms present in the JRM.

 

Maryam Souri

Optical Signatures of Spin-Orbit Exciton in Bandwidth Controlled Sr2IrO4 Epitaxial Films via High-Concentration Ca and Ba Doping           

We have investigated the electronic and optical properties of (Sr1-xCax)2IrO4 and (Sr1-yBay)2IrO4 (x and y = 0 - 0.375) epitaxial thin-films, in which the bandwidth is systematically tuned via chemical substitutions of Sr ions by Ca and Ba.  Transport measurements indicate that the thin-film series exhibits insulating behavior, similar to the Jeff = 1/2 spin-orbit Mott insulator Sr2IrO4.  The optical conductivity spectra of doped Sr2IrO4 shows that the increased U/W from (Sr1-xCax)2IrO4 to (Sr1-yBay)2IrO4 causes a red shift in spectral weight, which cannot be explained by the simple picture of well-separated Jeff = 1/2 and Jeff = 3/2 bands.  We suggest that the two-peak-like optical conductivity spectra of the layered iridates originates from the overlap between the optically-forbidden spin-orbit exciton and the inter-site optical transitions within the Jeff = 1/2 band.  Our experimental results are consistent with this interpretation as implemented by a multi-orbital Hubbard model calculation.

 

Samuel Teicher

Optical Parametric Amplification Effects in Two-Color Free-Electron Lasers

Newly available two-color X-ray free-electron lasers (XFELs) have raised questions with immediate experimental relevance: Are there optical parametric amplification effects in these systems? Can sum and difference-frequency generation (SFG and DFG) be achieved? These phenomena are explored using the broadband XFEL simulations Aurora and PUFFIN with the implication that SFG and DFG may be achievable with current hardware. SFG could prove to be a promising technique for boosting the XFEL frequency; very preliminary results are presented from an optimization study to this effect. In the particular case of SLAC National Accelerator Laboratory, this technique could may promise for achieving one of the lab’s overarching goals—single-shot protein structure determination—by allowing the LCLS XFEL to access frequency resonances for multi-wavelength anomalous diffraction studies.

 

Marie-Hélène Tremblay               

High-Performance Electron Acceptor with Thienyl Side Chains for Organic Photovoltaics

The poster presents the findings of Y. Lin et al. in the Journal of American Chemical Society (J. Am. Chem. Soc. 2016, 138, 4955−4961).

We develop an efficient fused-ring electron acceptor (ITIC-Th) based on indacenodithieno[3,2-b]- thiophene core and thienyl side-chains for organic solar cells (OSCs). Relative to its counterpart with phenyl side-chains (ITIC), ITIC-Th shows lower energy levels (ITIC-Th: HOMO = −5.66 eV, LUMO = −3.93 eV; ITIC: HOMO = −5.48 eV, LUMO = −3.83 eV) due to the σ-inductive effect of thienyl side-chains, which can match with high-performance narrow-band-gap polymer donors and wide-band-gap polymer donors. ITIC-Th has higher electron mobility (6.1 × 10−4 cm2 V−1 s−1) than ITIC (2.6 × 10−4 cm2 V−1 s−1) due to enhanced intermolecular interaction induced by sulfur−sulfur interaction. We fabricate OSCs by blending ITIC-Th acceptor with two different low-band-gap and wide-band-gap polymer donors. In one case, a power conversion efficiency of 9.6% was observed, which rivals some of the highest efficiencies for single junction OSCs based on fullerene acceptors.

 

Zhong Wan

Induced superconductivity in 2D system              

Induced superconductivity in semiconductors has been an area of active research for the last 20 years, and it gained a renewed attention recently with the search for states with non-Abelian statistics. Especially attractive is a combination of superconductivity and the quantum Hall effect as well as superconductivity in 1D semiconductor with strong spin orbit coupling. In the poster, I will present our progress on inducing superconductivity in GaAs 2D electron system as well as recent progress in InAs 2D electron system.

 

Jing Xu

Probing the origin of extremely large magnetoresistance in topological semimetals

The recent discovery of extremely large magnetoresistance (XMR) in the exotic topological Dirac and Weyl semimetals has triggered extensive research to uncover its origin. Both topologically protected surface states and bulk Dirac/Weyl fermions have been proposed as the cause of the observed XMR. XMR can also be associated with other mechanisms such as magnetic-field induced metal-insulator transition and electron-hole compensation. Here, we investigate novel transport phenomena in candidate topological semimetals with the focus on unravelling the origin of XMR and to establish methods to separate surface bulk transport effects, a major challenge even in the quintessential topological insulator Bi2Se3.

 

Jie Zhang

Multi-Photon Transitions in Coupled Plasmon-Cyclotron Resonance Measured by Millimeter-Wave Reflection

We construct a low-temperature microwave waveguide interferometer for measuring high-frequency properties of two-dimensional electron gases (2DEGs). Coupled plasmon-cyclotron resonance (PCR) spectra are used to extract effective mass, bulk plasmon frequency, and carrier relaxation times. In contrast to traditional transmission spectroscopy, this method does not require sample preparation and is nondestructive. PCR signals can be resolved with a microwave power source as low as 10 nW. We observe PCR in the multi-photon transition regime, which has been proposed to be relevant to the microwave-induced resistance oscillations.

 

Jihang Zhu

Josephson effect occurs at the surface of topological insulators

S-TI-S (superconductor-topological insulator-superconductor) Josephson junction is theoretically proved to be a candidate to support Majorana bound states. Then such a system (S-TI-S) is very important for basic study of Majorana fermions. My poster will introduce some S-TI-S systems and some results already achieved experimentally.

Published in 2017
Tuesday, 23 May 2017 09:13

On-Site Information

All meals are served at the Fresh Food Café located in the AMR complex on campus

A map provided by campus dining can be found here.  

Breakfast 7:45 am to 8:45am

Lunch 12:45pm to 1:45pm

Dinner 6:30pm to 7:30pm

 

Session Locations (lectures, poster sessions, etc) 

All sessions are held in the Bloomberg Building (Dept. of Physics and Astronomy)

See schedule for detailed locations.  Signs are posted in Bloomberg for the room locations.

A overall map of dining, housing, and lecture hall locations is here.   

General information about travel and lodging is here

 

Information about Baltimore

Additional information can be found here.

 

Emergency Contacts:

During office hours (9am to 5pm weekdays):  Maura Vonasek - 410-516-2372 - This email address is being protected from spambots. You need JavaScript enabled to view it.

Other times: Natalia Drichko - 410-516-6693 - This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Published in 2017

Program Dates & Location

June 5 - 16, 2017
Johns Hopkins University

 


Getting Here

The School will take place at the Johns Hopkins Homewood campus located in north Baltimore. The official address is 3400 N. Charles Str 21218 Baltimore. The East Gate to the Homewood Campus is located at a corner of 33rd Str and N. Charles Str. Please be attentive, JHU Homewood campus is not the Johns Hopkins hospital. The Homewood campus is easily accessible from several interstates, and is also a short taxi ride from Penn Station and the BWI airport.

If you are arriving to Baltimore by plane, you can take a taxi from Baltimore/Washington International Airport (BWI), it is about 35 minutes driving time to the Homewood campus, costs about $40. Alternatively, you can take Light Rail to the Penn Station, which is located much closer to the JHU Homewood campus, and take a taxi or a bus from there. The trip will cost $3.40 and about 40 min to Penn station, 1 hour the whole trip to JHU. The schedule of the Light Rail can be found here. Note: you need to change to a Light Rail which goes to Penn Station at Camden Yards or Convention center stops.

If you are arriving by train: Baltimore’s Penn Station is 10 minutes by taxi from the Homewood campus. At day time, you can also take a free bus Charm city circulator (Purple Route, to a stop 31st Street - Baltimore Museum Of Art, you’ll find yourself on the southern side of the Homewood campus. You can also take a bus #11 to the corner of N. Charles and 33rd Str ($1.70 exact cash paid on the bus). The bus stop is located on N. Charles str. half a block north from the Penn Station.

Here you can find driving directions to the Homewood campus of the Johns Hopkins University.


Housing and Meals

All participants will be staying in Charles Commons Residence Hall located at the corner of N. Charles street and 33rd Street, address: 3301 N. Charles Str, Baltimore 21218 MD. The building is across the street from the East Gate of the JHU Homewood campus. Bed sheets, pillow cases, etc. will be provided with your residence hall room but you should bring your own soap, shampoo, toiletries, etc. Please find more information about Charles Commons Residence Hall.

Charles Commons Residence Halls
Corner of North Charles Street and St. Paul Street
3301 North Charles Street
Baltimore, MD 21218

All housing details can be found in the Charles Commons brochure here.


Check-in and Registration

We expect you to arrive on Sunday, June 4, 2017.  Please note that the standard check-in time is 2pm-4pm but that the check-in desk is manned from 7am-midnight and on-call after hours. Dinner is the only meal available on Sunday June 4th.  Checkout is on Saturday June 17, 2017 between 8am-10am. Breakfast is the only meal included on Saturday, June 17.

The first lecture will take place Monday, June 5, 2017 at 8:40am in the auditorium 272 of the Bloomberg building which is situated about a 10 minute walk from the Charles Commons Residence Hall.

Lectures

All lectures (with any exceptions announced well in advance) will be held in the Bloomberg building, a 10-15 minute walk from Charles Commons Residence Hall. Typically there will be two lectures in the morning, 9:00am-12.30 pm with a coffee break 10.30-11 am, and one after-lunch lecture, panel discussion, or poster session at 2:00pm-3:30pm. Some additional seminars and discussions will also be held, with a final schedule posted on the website as soon as it's available.

All students are strongly encouraged to present a poster at the school. Details about the posters will be contained in the admission letter you receive. Location for discussions and poster sessions are forthcoming.

Copies of lectures notes will be available during the School. Soon after end of the School, these will also be available on the website. All talks will be videotaped and will be available online.

Library

Sheridan Libraries are found on Homewood campus: http://www.library.jhu.edu/about.html

Milton S. Eisenhower Library (a part of Sheridan Libraries) is opened 7 days a week, from 7.30 am to 3 am.


Mail

If you want to receive mail while attending NSF/DOE Quantum Science Summer School (QS3), please use the following address:

Quantum Science Summer School (QS3)
Dept. of Physics and Astronomy
Johns Hopkins University
3400 N. Charles Street
Baltimore 21218 MD

Please make sure not to list this address for mail you will continue to receive after you leave the school (ex. magazine subscriptions).

The phone number for the Department of Physics and Astronomy is: 410-516-7347 | Fax: 410-516-7239


Insurance

The Johns Hopkins University, NSF and DOE does not take out any health or accident insurance for the lecturers and participants of the Quantum Science Summer School; this is your individual responsibility.

 
Published in 2017
Friday, 24 February 2017 11:12

Baltimore, MD Information

 

 

 

The Johns Hopkins University is located in Baltimore, the largest city in Maryland, and one of the oldest cities in the United States. The beautiful Homewood campus of the University, where the school will take place, is set on the northern side of downtown. In summer months Baltimore can be hot and humid, although in June the summer heat has usually not yet arrived.  Warm summer evenings are a nice time to hang out with friends on campus or in the cafes and bars of the colorful nearby Charles Village or Hampden urban neighborhoods, reachable in 5-15 minutes by foot.

One can get to Baltimore’s attractive historic downtown from Homewood Campus in 15 minutes by a bus or a car. The heart of the Baltimore downtown is its harbor with beautiful urban views, many places to go out, the National Aquarium, and the historic boats it hosts. Baltimore is full of important sites for American history, such as Fort McHenry, the Star-Spangled Banner Flag House and more.  Baltimore boasts world-class art galleries, such as the Walters Art Museum and the Baltimore Art Museum, the latter of which is located on the southern side of the Homewood campus.  It is also close to Washington D.C. for weekend excursions.

 

Published in 2017