Baltimore Colloquium on Quantum Computing

The Baltimore Chapter of Electron Devices and Solid-State Circuits will be hosting its fifth Fall Colloquium on October 12, 2016.  The theme of this year’s meeting is Quantum Computing.  This one-day event features a variety of experts in multiple aspects of the field: Superconducting Electronics, Optical Computing, and Ion Traps.  Attendance is open to industry, government, and academia, including students.  The venue is once again the American Center for Physics (conference room A), one mile southeast of the University of Maryland College Park campus.  For location and directions see http://www.acp.org/directions-american-center-physics.

Admission and parking are free, but registration is required (below).  Complimentary lunch will be provided for those who register by October 7.  Attendance is limited to 60; if you are not able to register via this site, please contact the chapter secretary papotyraj@ieee.org.

Agenda:

09:00 Registration: Coffee & Donuts

09:45 Opening Remarks

09:55 Dr. Kathy-Anne Soderberg, Air Force Research Laboratory, Information Directorate: “Quantum Networking and Quantum Computing at AFRL“

10:30 Dr. Joel Strand, Northrop Grumman: “Controlling Superconducting Qubits with Josephson Junction Logic“

11:05 Dr. Jim Franson, UMBC: “Nonlinear Properties of ‘Linear’ Optical Amplifiers”

11:40 Dr. Jim Freericks, Georgetown University: “Measuring Excitation Energies and Green’s Functions in Ion-Trap-Based Quantum Simulations”

12:15 Lunch Break (complimentary lunch provided for registered attendees) 

01:00 Dr. Norbert Linke, UM Joint Quantum Institute: “Quantum Algorithms on a Programmable Ion Trap Quantum Computer”

01:35 Dr. Jiehang Zhang, UM Joint Quantum Institute: “Non-equilibrium Dynamics in an Ion Quantum Simulator”

02:10 Dr. Shuo Sun, UM Joint Quantum Institute: “Quantum Information Processing with Quantum Dot Spins Coupled to Nanophotonic Cavities“

02:45 Coffee Break

03:00 Dr. Michael Foss-Feig, Army Research Lab: “Entanglement Growth and Locality in Long-Range Interacting Quantum Systems”

03:35 Dr. Fredrik Fatemi, Army Research Lab: “Exciting Modes of Optical Nanofibers”

04:10 Dr. Brian Kirby, ARL Network Science Division, “Quantum Network Engineering”

04:45 PM – Concluding Remarks

05:00 PM – Adjourn

Agenda:

Dr. Joel Strand:  Controlling superconducting qubits requires shaped microwave pulses and, in most control schemes, fast flux bias to achieve the requisite rotations around the Bloch sphere and frequency shifts to accomplish a complete set of one and two qubit gates.  Sourcing all these control signals at room temperature presents an imposing hardware challenge, but Reciprocal Quantum Logic (RQL) is a Josephson junction based digital logic that could provide a low power cryogenic source of control signals. We report on the design, simulation, and test of Josephson junction-based output amplifiers, microwave switches, phase shifters, and balanced modulators operating in the 5-10 GHz range.  The devices are controlled by F₀-level base-band signals, operate with no power dissipation on chip, and have greater than -70 dBm saturation power, making these devices suitable for control of quantum devices.

Dr. James Franson:  Optical amplifiers play a crucial role in classical communications, where they are used to overcome the loss in optical fibers, for example.  At the quantum level, an ideal optical amplifier will introduce an unavoidable amount of noise that must be taken into account in considering their use in applications such as quantum communications and quantum sensors.  An ideal optical amplifier has long been considered to be a linear device, but we recently showed that entanglement between the signal and the amplifying medium can produce large amounts of decoherence that is unrelated to the added noise.  In fact, this effect can degrade the performance of an amplifier even when the added noise is negligibly small.  The quantum-mechanical origin of these effects will be discussed and their impact on the amplification of Schrodinger cat states will be described.

Dr. Jim Freericks:  One of the hallmarks of quantum simulation is adiabatic state preparation, where a system starts in the ground state of a trivial Hamiltonian and is slowly evolved to the ground state of a complex Hamiltonian, which then can be used for further quantum computing or can have its properties analyzed.  Since most experiments cannot evolve the system over a long-enough time to maintain adiabaticity, and because shortcuts to adiabaticity are difficult to achieve, most quantum simulators create significant diabatic excitations.  One can directly study these excitations, by performing spectroscopy to extract the excitation energies, or by using Ramsey-type experiments to extract effective spin-spin Green’s functions.  In this talk, I will describe how one performs such spectroscopy and discuss the information contained in the Green’s functions.

Dr. Norbert Linke:  Trapped atomic ions provide pristine “atomic clock” qubits and optical schemes for near-unity state preparation and measurement.  We present a modular quantum computing architecture comprised of a chain of Ytterbium ions with individual Raman beam addressing and individual readout [1].  We employ a pulse-shaping scheme [2] to use the transverse modes of motion in the chain to produce entangling gates between any qubit pair.  This creates a fully connected system which can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable quantum computer.  To demonstrate the universality of this setup, we present experimental results from quantum algorithms on five ions.

Dr. Jiehang Zhang:  We engineer synthetic quantum matter by encoding spins in a linear chain of trapped 171Yb+ ions.  By applying laser-driven spin-dependent transitions, we generate an effective long-range Ising Hamiltonian, mediated through the collective normal modes of motion.  Furthermore, we apply individual control fields to realize arbitrary state preparation, as well as programmable random disorder.  Such a well-controlled quantum system provides an ideal platform for quantum simulations, where the classical computation resources required scales exponentially as the system size grows.  With these tools, we present some recent studies on intriguing questions regarding to quantum thermalization and novel driven phases of matter.  We study “prethermalization”, the failure of thermalization due to quasi-conserved quantities.  We also present the first observation of a “discrete time-crystal”, a novel temporal-correlated states which breaks discrete time-translation sysmmetry.

Dr. Shuo Sun:  The spin of a single electron confined in a quantum dot is a promising matter qubit for quantum information processing.  This spin system possesses microsecond coherence time and allows picosecond timescale control using optical pulses.  It is also embedded in a host semiconductor material that can be directly patterned to form compact integrated nanophotonic devices.

Dr. Michael Foss-Feig:  For more than a decade, ultracold atomic and molecular systems have been exploited to simulate canonical models of strongly correlated materials.  However, the extremely low (often sub nano-kelvin) temperatures required to realize the most interesting equilibrium behaviors of such models, including quantum magnetism and high-temperature superconductivity, have proven extremely difficult to achieve.  When these ultracold systems are driven far-from equilibrium, however, very small temperatures get traded in for very long time-scales, which enable the observation of dynamic phenomena that were never even envisioned in the context of real materials.  In this talk, I will review some recent experimental and theoretical explorations of non-equilibrium dynamics in ultracold atomic systems, and will discuss some of the interesting questions that arise naturally from their remarkable tunability.  In particular, I will describe recent efforts to understand the fate of locality — i.e. constraints on the propagation of information/entanglement — as interactions become increasingly long-ranged.

Dr. Fredrik Fatemi:  Optical nanofibers (ONFs) – fibers drawn to subwavelength diameters – can have a strong evanescent field that efficiently interacts with surrounding atoms or quantum systems. One benefit of ONFs is that they are drawn from standard optical fiber that connects well with traditional optical hardware (detectors, laser diodes, etc), but this requires adiabatic tapering for efficient transmission.  In this talk, I describe the use of higher order optical modes not only to observe interesting propagation behavior, but also to measure the ONF radius with 40 picometer sensitivity.  I will also describe some upcoming experiments we have with trapped cold atoms.

Dr. Brian Kirby:  The establishment of quantum networks will enable several interesting applications such as secure communication, distributed quantum computing, and enhanced metrology.  Quantum networks are comprised of interconnected nodes which are capable of storing, manipulating, and transmitting entangled quantum states.  In this talk we review recent efforts by our group at ARL to understand how entanglement can be distributed between these nodes in the presence of imperfect channels.  First we study the effects of polarization dependent loss, a common issue in optical fibers, on entangled qubit pairs. Further, we consider the effects of various channel decoherence mechanisms on entanglement swapping, and suggest how networks can be designed to mitigate these.  Lastly, we describe a topology for entanglement-distribution switching networks which is optimized over worst case loss and the number of switches used.

Location:
Room: Conference Room A
Bldg: American Center for Physics
One Physics Ellipse
College Park, Maryland
20740