Dr
Horst Simon
(Lawrence Berkeley National Laboratory)
26/01/2019, 09:30
Prof.
Motoko Kotani
(RIKEN)
26/01/2019, 09:53
Dr
Tetsuo Hatsuda
(RIKEN)
26/01/2019, 10:16
Jonathan Carter
(Lawrence Berkeley National Lab)
26/01/2019, 10:40
Igor Markov
(University of Michigan)
26/01/2019, 11:30
Foundations of quantum computing
The leading candidate task for benchmarking quantum computers against classical computers
entails sampling from the output distribution defined by a random quantum circuit. We develop a massively-parallel simulation package that does not require inter-process communication (IPC) or proprietary hardware. We introduce two ways to trade circuit fidelity for computational speedups, so as to match...
Dr
Riccardo Manenti
(Rigetti)
26/01/2019, 12:15
Foundations of quantum computing
The immense power of quantum computation is illustrated by flagship quantum algorithms that solve problems, such as factoring, much more efficiently than classical algorithms. The building of a quantum device with error rates well below the fault-tolerance threshold poses a challenge to the implementation of these quantum algorithms on near-term devices. In this talk, I will present the...
Dr
Nathan Shammah
(RIKEN)
26/01/2019, 14:30
Open-source tools and quantum machine learning
I address the growth of open-source software in scientific research and quantum technology research in particular, both in academia and industry. I will give a brief overview of multiple open-source libraries being developed to study quantum systems, using a variety of hybrid techniques, from chemistry to machine learning. QuTiP, the Quantum Toolbox in Python, has established itself as a major...
Wibe de Jong
26/01/2019, 15:15
Open-source tools and quantum machine learning
The Quantum Algorithms Team led out of Lawrence Berkeley National Laboratory is an integrated team of quantum algorithm developers, mathematicians, and computer scientists with a mission to deliver algorithmic, computational and mathematical advances to enable scientific discovery in chemical sciences on quantum computers. Our focus is on quantum chemistry simulations, which are an early...
Mr
Kosuke Mitarai
(Osaka University)
26/01/2019, 16:30
Open-source tools and quantum machine learning
We propose a classical-quantum hybrid algorithm for machine learning on near-term quantum processors, which we call quantum circuit learning. A quantum circuit driven by our framework learns to perform a given task by tuning parameters implemented on it. We also provide a way to obtain an analytical gradient of an expectation value of an observable for gradient-beased optimization of...
Dr
Stephen Holland
(LBNL)
26/01/2019, 17:00
We describe the development of charge-coupled devices (CCDs) capable of detecting single electrons. The CCDs utilize a non-destructive readout amplifier that allows for the multiple sampling of the signal charge with a corresponding reduction in the read noise by the inverse square root of the number of samples. The CCDs have been fabricated on high-resistivity silicon that enables the full...
Prof.
Matt Pyle
(University of California Berkeley)
26/01/2019, 17:30
Searching for dark matter in the 10meV-100MeV mass range requires sensitivity to small energy depositions. In particular, sensitivity to a single optical phonon quanta in Sapphire ( ~ 50meV) or 2 roton quanta in superfluid He would enable searches deep into an entirely unexplored parameter space. Over the past year, we’ve made significant progress towards these goals. In particular, we’ve...
Prof.
Hidetoshi Nishimori
(Tokyo Institute of Technology)
27/01/2019, 09:30
Quantum enhanced optimization
After an introduction and an overview of quantum annealing, I describe recent developments in non-traditional protocols to control quantum effects for enhanced performance: (i) non-stoquastic drivers [1], (ii) spatially inhomogeneous driving of the field [2], and (iii) reverse annealing [3]. I will show explicit examples in which first-order quantum phase transitions can be avoided by these...
Dr
Shunji Matsuura
(1QBit)
27/01/2019, 10:15
Quantum enhanced optimization
While quantum algorithms are believed to be more powerful than classical algorithms, the computational power of near term quantum devices is highly
restricted because of noise.
In order to overcome the limitations and exploit quantum advantages on noisy quantum devices, it is important to develop algorithms which complete each run of quantum computation within a short coherence...
Dr
Arjun Gambhir
(Lawrence Livermore National Laboratory)
27/01/2019, 10:45
Quantum enhanced optimization
Numerous fields require numerically solving a system of linear equations. For equations stemming from large, sparse matrices, this is classically done with iterative methods and judicious preconditioning. Convergence of such algorithms can be highly variable and depends in part, on the condition number of the matrix. With the arrival of quantum computing in the Noisy Intermediate-Scale Quantum...
Prof.
K. Birgitta Whaley
(UC Berkeley)
27/01/2019, 11:30
Quantum enhanced optimization
I shall present an approach to continuous error correction with application to error correction of quantum annealing. Our approach is based on use of weak measurements and quantum feedback, together with quantum error correcting codes. I shall present preliminary results using both error detecting and error correcting codes, and discuss the relative benefits of different paradigms of quantum...
Prof.
Daniel Lidar
(USC)
27/01/2019, 12:00
Quantum enhanced optimization
As quantum computing proceeds from perfecting physical qubits towards testing logical qubits and small scale algorithms, an urgent question being confronted is how to decide that critical milestones and thresholds have been reached. Typical criteria are gates exceeding the accuracy threshold for fault tolerance, logical qubits with higher coherence than the constituent physical qubits, and...
Mr
Kabuki Takada
(Tokyo Institute of Technology)
27/01/2019, 12:30
Quantum enhanced optimization
Studying phase transitions of the transverse-field Ising model is significant from the viewpoint of quantum annealing. Presence of a first-order phase transition is one of the most serious problems because it makes computation time of quantum annealing exponentially large as a function of the system size. We consider the frustrated Ising ladder in a transverse field, which is known to exhibit...
Andreas Scholl
(Lawrence Berkeley Lab)
27/01/2019, 14:30
Condensed matter applications
I will lead in by giving a brief overview over the Advanced Light Source and over techniques that may be of interest to the QIS and in particular the quantum materials community. I will then discuss two examples: Photoemission Electrion Microscopy (PEEM), which was used to study the ground state and thermal dynamics of artificial spin ice systems and soft x-ray interferometry, which we used to...
Xiaoqian Chen
(Lawrence Berkeley National Laboratory)
27/01/2019, 15:00
Condensed matter applications
As we explore new materials harboring entangled quantum states, an efficient probe for their detection is necessary. Coherent x-rays are a direct probe for equilibrium and nonequilibrium dynamics that can simultaneously measure a large number of particles. In my talk, I will use our recent work on dipolar-coupled artificial spin lattices (ASL) and explore the possible route to use coherent...
Mr
Haokun Li
(University of California, Berkeley)
27/01/2019, 15:30
Condensed matter applications
The interaction of macroscopic mechanical object with electron charge and spin plays a vital role in today’s information technology and fundamental studies of the quantum-classical boundary. Recently emerged valleytronics encodes information to the valley degree-of-freedom and promises exciting applications in communication and computation. We realize valley-mechanical coupling in a monolayer...
Dr
Michael Fraser
(RIKEN CEMS / JST PRESTO)
27/01/2019, 16:30
Condensed matter applications
Emerging research in topological photonic systems promises new ways to control light flow without dissipation and the possibility of creating new functional photonic devices exploiting topology. Creating topological states in the microcavity exciton-polariton system would represent a topological photonic platform where interactions might further be used to control strongly-correlated...
Dr
Eli Rotenberg
(LBNL)
27/01/2019, 17:00
Condensed matter applications
Angle-resolved photoemission spectroscopy (ARPES) is a premier tool for determining the charged excited states of quantum materials. It directly measures the single particle spectral function $A(k,\omega)$ that encodes the renormalized lifetime and energy of quasiparticle states as a function of momentum ($k$) and energy ($\omega$). ARPES is complementary to both scanning tunneling microscopy...
Prof.
Dong Yu
(U.C. Davis)
27/01/2019, 17:30
Condensed matter applications
Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature, and exciton condensates can be realized at much higher temperature than condensates of atoms because of strong Coulomb binding and small mass. Signatures of exciton condensation have been reported in double quantum wells, microcavities, graphene, and transition...
John Clarke
(University of California, Berkeley)
28/01/2019, 09:30
Quantum sensing
The Josephson tunnel junction consists of two superconductors separated by a thin insulating barrier through which, at low electrical currents, Cooper pairs of electrons can tunnel without producing a voltage. When the applied current is increased above a value known as the critical current, however, a voltage is developed. The dc Superconducting QUantum Interference Device (SQUID) consists of...
Dr
Aritoki Suzuki
(Lawrence Berkeley National Lab)
28/01/2019, 10:10
Quantum sensing
Transition edge sensors (TES) are work horses of physics experiments. In pursuit for more sensitivity, experiments such as Cosmic Microwave Background (CMB) polarimetry experiments and neutrino-less double beta decay experiments are increasing number of sensors. As TES operate at sub-Kelvin temperature, highly multiplexed, low-noise and low power dissipation multiplex readout technique is a...
Dr
Gianpaolo Carosi
(Lawrence Livermore Natl Lab)
28/01/2019, 10:35
Quantum sensing
One of the most interesting problems in physics and cosmology today is what makes up dark matter. The QCD axion is a well motivated candidate and is predicted to be very light ($\mu$eV mass) and very cold, meaning it would interact more like a radio wave then an ionizing particle. The Axion Dark Matter Experiment (ADMX) uses the "haloscope technique" to search for axions resonantly converting...
Prof.
Seigo Tarucha
(RIKEN CEMS / University of Tokyo)
28/01/2019, 11:30
Qubit architectures
To date basic techniques of implementing spin-based quantum computing have been developed using quantum dots, including single and two-qubit gates, initialization and readout. But improving the operation fidelity as well as increasing the qubit number is still a challenge in realizing fault-tolerant quantum computing. We have developed a fast gating technique for Si quantum dots to operate the...
Dr
Keiji Ono
(RIKEN)
28/01/2019, 12:10
Qubit architectures
Spin qubits are attractive building blocks for quantum computers. Si is a promising host material for spin qubits since it could enable long coherence, high-density integration, and high compatibility with classical computers. Spin qubits have been implemented in Si using gate-defined quantum dots or shallow impurities. However, these qubits must be operated at temperatures <0.1 K, limiting...
Dr
Emi Yukawa
(CEMS, RIKEN)
28/01/2019, 12:35
Qubit architectures
We propose a scheme to generate macroscopic superposition states (MSSs) of two classically distinct states in spin ensembles where a coherent driving field is applied to accelerate the process of generating MSSs via a nonlinear interaction [1]. The numerical calculation demonstrates that this approach allows one to generate a superposition of coherent spin states (CSSs) of the spin ensemble...
Prof.
Hartmut Haeffner
(UC Berkeley)
28/01/2019, 14:30
Qubit architectures
With exceptional coherence and gate fidelities, trapped ions offer unique opportunities to process quantum information. As a consequence quantum algorithms with up to 20 ions have been implemented on trapped-ion quantum computers. To take the next steps will require the research community to take on the engineering challenges as well as exploring improving fundamental aspects.
I will...
Dr
Joshua Isaacs
(UC Berkeley)
28/01/2019, 15:00
Qubit architectures
Electrically neutral dipolar molecules prepared in the absolute ground state represent one of the newest additions to the quantum-information and simulation family tree. Prepared in the lowest rotational state ($N=0$), and in the absence of a polarizing electric field, neutral dipolar molecules lack a lab-frame electric dipole moment (EDM). However, admixing components of higher rotational...
Dr
Machiel Blok
(UC Berkeley)
28/01/2019, 15:30
Encoding quantum information in the higher energy levels of the transmon circuit provides a hardware efficient way to harness a larger Hilbert space in existing quantum processors while also increasing their connectivity. Furthermore, a network of qutrits (three-level systems) is naturally suited to experimentally demonstrate recently identified connections between high energy physics and...
Dr
Takeshi Fukuhara
(RIKEN CEMS)
28/01/2019, 17:15
Qubit architectures
Ultracold atoms, which are gaseous atoms cooled to the quantum regime by laser cooling and evaporative cooling, provide ideal platforms to study many-body quantum systems. Especially, such atoms loaded into in periodic potential (optical lattice) created by laser beams can be used to “simulate” fundamental condensed-matter models, such as the Hubbard model or the Heisenberg spin model. In this...
Dr
Michihisa Yamamoto
(RIKEN Center for Emergent Matter Science)
28/01/2019, 17:45
Qubit architectures
Varieties of solid-state quantum bits have been investigated, among which the most prominent are superconducting quantum circuits and semiconductor quantum dots. All of them are defined as “localized” quantum two-level systems. Benefits of using such localized systems are isolation of qubits from their environment and potential ability to control individual qubits and inter-qubit coupling with...
Dr
Sinéad Griffin
(Lawrence Berkeley National Laboratory)
29/01/2019, 10:00
Quantum sensing
The direct detection of light dark matter (DM) relies on harnessing low-threshold events in target materials. Here I will discuss two proposals for the direct detection of light DM; Dirac materials and polar semiconductors. Using first-principles methods, we calculate the material-specific matrix elements, and show that DM scattering in an anisotropic crystal has a strong directional...
Prof.
Daniel McKinsey
(UC Berkeley)
29/01/2019, 10:30
Quantum sensing
We propose a new technology for dark matter direct detection, using superfluid helium as the target material. Superfluid helium has many merits as a detector target; these include good kinematic matching to low mass dark matter, feasibility for achieving good intrinsic radiopurity, multiple signals to enable radioavtive and instrumental background rejection, and its unique ability to be cooled...
Dr
Vivek Singh
(University of California, Berkeley)
29/01/2019, 11:30
Quantum sensing
CUPID (CUORE Upgrade with Particle ID) is a next-generation tonne-scale experiment that will use arrays of low-temperature calorimeters to search for rare processes like neutrinoless double beta decay. While CUORE (Cryogenic Underground Observatory for Rare Events) has already demonstrated the concept of operating a tonne-scale array at low temperatures (~10 mK), CUPID aims to significantly...
Dr
Brent VanDevender
(Pacific Northwest National Laboratory)
29/01/2019, 12:00
Quantum sensing
Excess quasiparticles are universally observed to limit coherence times in superconducting qubits. It is hypothesized that natural radiation in the laboratory environment could be the cause. We will review the evidence for excess quasiparticles and explore our hypothesis that environmental radiation is the source of them. Plans for an imminent experiment to test the hypothesis by placing a...
Prof.
Holger Müller
(UC Berkeley)
29/01/2019, 12:30
Quantum sensing
Quantum technology enables new measurements and thus new insights in fundamental physics, applied physics, chemistry, and biology. We will discuss two examples:
Using interference of matter waves, we have recorded the most precise measurement of the fine structure constant, at 0.20-part-per-billion accuracy. Comparison with Penning trap measurements of the electron gyro-magnetic anomaly is...
Thomas Schenkel
29/01/2019, 14:30
Quantum sensing
Color centers, such as the nitrogen-vacancy center center in diamond are being used in early quantum sensing applications (e. g. as magnetometers) and they are promising spin-photon qubits with ms-scale coherence times at room temperature. In my presentation I will discuss challenges and opportunities for the further development of NV- centers (e. g. formation efficiency and deterministic...
Soonwon Choi
(University of California Berkeley)
29/01/2019, 15:00
Quantum sensing
One of the most promising routes towards high-sensitivity quantum metrology is to utilize high density spin ensembles. However, as the density of a spin ensemble is increased, strong spin-spin interactions can impose a limit to the coherence time and thus the maximum achievable sensitivity. In this talk, we will discuss two promising methods to overcome this limitation. In the first approach,...
Mr
Shubhayu Chatterjee
(UC Berkeley)
29/01/2019, 15:30
Quantum sensing
Two-dimensional magnetic insulators exhibit a plethora of competing ground states, such as ordered (anti)ferromagnets, quantum spin liquids characterized by topological order and anyonic excitations, and random singlet phases emerging in the presence of disorder and frustration. Single spin qubits, which interact directly with the low-energy spin-excitations of magnetic insulators, can be used...
