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I am attending the conference celebrating 20 years of superconducting circuits in quantum information science and quantum optics. It’s being held where the first experimental observation of cooper pair boxes macroscopic coherence was observed: in Tsukuba, Japan. 
Opening the conference is cochair Y. Nakamura (@UTokyo_News_en @riken_en). Following, overview by M. Devoret (@Yale_QI). Quality factors of artificial atoms now compare to Hydrogen atom linewidths. Steady improvement of coherence times. Now robustness with GKP states. @preskill.
A. Clerk (@UChicagoIME) obtains pure quantum states with reservoir engineering of one and two photon drive and dissipation. QuTiP is acknowledged in the slides: if you are attending, check out recent developments of QuTiP, my poster is P06.@circuitqed @NumFOCUS @IQ_USherbrooke
Here is the conference website cems.riken.jp/sq20th/index.h… I would like to acknowledge that M. Devoret gives the inaugural lecture *and* will present a poster later. You’re never too “big” to present a poster. A possible future Nobel awardee (?) enjoying physics at a poster session.
Second session: A. Kandala (@IBMResearch) adresses error mitigation on real quantum chips by artificially amplifying noise to infer better data points.
K. Fujii @fgksk (@osaka_univ_e) presents theoretical research on quantum machine learning: variational eigensolver and differentiation of quantum circuits. Applications of QML to quantum chemistry and gate optimization to improve two-qubit gate fidelity. Simulations with QuTiP.
Ted White (@GoogleAI Quantum): superconducting circuit technology went from single qubit control to tens of qubits on a chip. This regime poses challenges on multiple levels: architecture (how to connect qubits, what qubits), electronic control, calibration.
NISQ devices: still looking for applications, need to find NISQ algorithms as error corrected codes are far away. Current focus at @GoogleAI is on the quantum supremacy experiment of random circuits, in which the distribution of bitstrings follows a specific distribution.
The Bristlecone chip contains 72 qubits and is used for the quantum supremacy experiment. The gmon approach has some technical architecture challenge but reports 99,5% fidelity for arbitrary two-qubit gates, on a chip with 18 qubits (article still in preparation).
A. Houck (@Princeton) reports on his lab’s research on a new kind of qubit for quantum computing, going beyond the transmon. Implementing a 0-pi transition would intrinsically protect against de-excitation (T1) and dephasing (T2). Preliminary results @ T1=150 microsecond, T2=50.
K. Semba (NICT) reports on record light-matter interaction strengths in an artificial atom-cavity system on superconducting circuits. This platform has allowed to achieve ever greater couplings: from weak to strong, “ultra-strong”, and “deep-strong”, i.e. ~ bare frequencies.
F.K. Wilhelm (@Saar_Uni @OpenSuperQ): new techniques in optimal control to improve gate fidelities by pulse design. @QuantumFlagship will open-source algo using machine learning + GOAT @TensorFlow. Applied the protocol to @IBMResearch Zurich device. Need to recalibrate daily.
Poster session: M. Gely (@tudelft) made an open-source library in Python with GUI to draw electrical circuits (including superconducting circuit qubits) to obtain a Hamiltonian’s properties, using QuTiP. The simulations allow to interpret their results from the lab.
I found more information at qucat.org. Cc @quantshah.
The last session of the day: a talk by P. Bertet (@CEAParisSaclay), reporting on his group's results on the Purcell effect and electron spin resonance in solid state, and Dany Lachance-Quirion (@UTokyo_News_en) on the new field of quantum magnonics. arxiv.org/abs/1902.03024
2nd day of SQ20th: A. Blais @circuitqed (@IQ_USherbrooke) opens the first session with a theoretical model, experiment @UCBerkeley, for a microwave single photon detector, with a broadband metamaterial. Keldysh integrals + matrix product state calculations match. @arne_grimsmo
B. Huard (@UniversiteLyon) and his team built and characterized a device based on fluorescence that allows to detect N photons. Excellent agreement with Lindblad master equation.
A.N. Jordan (@UofR): from prehistory to emergent chaotic dynamics from quantum trajectories and weak measurements, akin to probing the flight of a butterfly vs just looking where it lands. He emphasizes that in this field experiments proved many exotic theoretical predictions.
M. Mirrahimi (@inria_paris): cat qubits with error correction using noise.
L. Sun (@Tsinghua_Uni) reports on experimental quantum error correction with binomial bosonic codes. Applying Optimal control (GRAPE algo) and using quantum error correction also to enhance metrology.
Some more slides from Sun’s lab impressive experiments at @Tsinghua_Uni.
L. DiCarlo (@QuTech_news) gives information on Delft’s approach to quantum computing: aiming at quantum error correction. The group has a full stack, open source approach. Architecture w @intel: 3D chip readout, starmon qubit. Qblox is an upcoming startup selling components.
A.N. Cleland (@UChicagoIME) gives an overview of the progress in surface acoustic waves interacting with qubits on superconducting circuits. Phonons are slow bosons that his lab used to control qubits, Wigner tomography, remote entanglement sharing.
More slides on experimental data and details from Cleland’s lab.
More slides from K. O’ Brien’s talk.
This last session of the day focuses on technological progress in nonlinear components that are crucial in experiments on superconducting circuits for labs doing quantum information and compitation. M. Hatridge (@PittTweet) reports on progress in multi-mode parametric amplifiers.
Last day of SQ20th: O.V. Astafiev (@RoyalHolloway @Skoltech) introduces to the conference the phase-slip qubit and the charge quantum interference device (CQUID), and compares it to the SQUID.
This tweet from yesterday got missing in the thread
H. Pothier (@CEAParisSaclay) celebrated the Josephson Junction-based qubit 20 years later. He explains the physics of Andreev reflection and Andreev bound states and how to modify the complex band structure to obtain new qubits in superconducting circuits.
G. Catelani (Jülich RC): quasiparticles affect relaxation times and overall performance of coherent dynamics in superconducting qubits (and even the stability of qubits themselves). The quasiparticle dynamics can be modeled and effect poisoning controlled.
More slides on discerning different effects in quasiparticle dynamics.
D. Schuster @schusterqed (@UChicagoIME) is exploring quantum error correction with qutrit pairs as a very small logical qubit robust against photon emission. Also exploring heavy fluxonium qubits. Millisecond relaxation times reported.
I. Ozfidan (@dwavesys) reports on the experimental implementation of a non-stoquastic Hamiltonian in two coupled superconducting qubits. Simulations for two-level systems fit the data. The transverse Ising model is obtained extending quantum annealing capabilities.
B. Plourde (@SyracuseU) aims at reducing noise sources by placing digital control of superconducting qubits inside the fridge without microwave pulses. Single flux quanta allow to implement classical logic. Devices are produced in collaboration with SeeQC, a components startup.
R. Schoelkopf (@Yale_QI) reports on his labs tests on logical qubits with error correction using bosonic degrees of freedom. Parity protects against qubit flips. Gates are optimized with optimal control (GRAPE) and logical qubits show better fidelities.
X. Zheng (USTC) shows many experimental results from his lab: GHZ tomography of 10-qubit state, entanglement witness on a 12-qubit chip, and more details on the open source quantum cloud.
Zhu’s team has also implemented a quantum walk experiment with 12 qubits (Science 2019). 24-qubit chip tested (soon in PRL). They began the designs for a 50-qubit chip, considering both a square geometry and a qubit chain. Possible quantum supremacy still years away.
F. Deppe (WMI) reports on the combined achievement of secure quantum remote state preparation and squeezed microwave states in superconducting circuits using Josephson parametric amplifiers. Over 16 decibel of squeezing. arxiv.org/abs/1902.00453
1.6 dB.
O. Painter (@caltech) opens the last session of the conference with beautiful results on waveguide QED. Two and more (up to 10) atoms are connected through a common waveguide and can exhibit superradiance and subradiance in the strong coupling regime. Augmenting SC connectivity.
A. Wallraff @AndreasAtETH @qudev (@ETH_physics) provides a summary of his lab’s results implementing cavity QED with superconducting circuits at microwave wavelengths.
.@qudev latest results include implementing a single photon detector on a device architecture previously used for probing a variety of cavity QED effects. It works as a parity detector too and directly measures the Wigner function of the traveling photon.
J.S. Tsai (TUS @riken_en), co-chair of the conference gives some concluding remarks. History of the superconducting qubit included many contributions. The technology went through a valley of death. NEC at the time was top tech company. I add that qubit count is not a good metric.
My poster on QuTiP: github.com/nathanshammah/…. For a perspective with @quantshah on open source quantum tech beyond QC: blogs.nature.com/onyourwaveleng…. End of thread!
@threadreaderapp please unroll.
