scholarly journals Coherent manipulation of an Andreev spin qubit

Science ◽  
2021 ◽  
Vol 373 (6553) ◽  
pp. 430-433 ◽  
Author(s):  
M. Hays ◽  
V. Fatemi ◽  
D. Bouman ◽  
J. Cerrillo ◽  
S. Diamond ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Quantum Information Processing ◽  
Coherence Time ◽  
Single Shot ◽  
Circuit Quantum Electrodynamics ◽  
Semiconductor Nanowire ◽  
Superconducting Circuits ◽  
Raman Transitions ◽  
Spin Qubit ◽  
Coherent Spin

Two promising architectures for solid-state quantum information processing are based on electron spins electrostatically confined in semiconductor quantum dots and the collective electrodynamic modes of superconducting circuits. Superconducting electrodynamic qubits involve macroscopic numbers of electrons and offer the advantage of larger coupling, whereas semiconductor spin qubits involve individual electrons trapped in microscopic volumes but are more difficult to link. We combined beneficial aspects of both platforms in the Andreev spin qubit: the spin degree of freedom of an electronic quasiparticle trapped in the supercurrent-carrying Andreev levels of a Josephson semiconductor nanowire. We performed coherent spin manipulation by combining single-shot circuit–quantum-electrodynamics readout and spin-flipping Raman transitions and found a spin-flip time TS = 17 microseconds and a spin coherence time T2E = 52 nanoseconds. These results herald a regime of supercurrent-mediated coherent spin-photon coupling at the single-quantum level.

scholarly journals Electron shelving of a superconducting artificial atom

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nathanaël Cottet ◽  
Haonan Xiong ◽  
Long B. Nguyen ◽  
Yen-Hsiang Lin ◽  
Vladimir E. Manucharyan
Keyword(s):  
Quantum Electrodynamics ◽  
Optical Pumping ◽  
Radiative Lifetime ◽  
Resonant Cavity ◽  
Coherence Time ◽  
Fluorescence Signal ◽  
Circuit Quantum Electrodynamics ◽  
Artificial Atom ◽  
Cavity Modes ◽  
Quantum Technology

AbstractInterfacing long-lived qubits with propagating photons is a fundamental challenge in quantum technology. Cavity and circuit quantum electrodynamics (cQED) architectures rely on an off-resonant cavity, which blocks the qubit emission and enables a quantum non-demolition (QND) dispersive readout. However, no such buffer mode is necessary for controlling a large class of three-level systems that combine a metastable qubit transition with a bright cycling transition, using the electron shelving effect. Here we demonstrate shelving of a circuit atom, fluxonium, placed inside a microwave waveguide. With no cavity modes in the setup, the qubit coherence time exceeds 50 μs, and the cycling transition’s radiative lifetime is under 100 ns. By detecting a homodyne fluorescence signal from the cycling transition, we implement a QND readout of the qubit and account for readout errors using a minimal optical pumping model. Our result establishes a resource-efficient (cavityless) alternative to cQED for controlling superconducting qubits.

scholarly journals Quantum-information processing with circuit quantum electrodynamics

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
Alexandre Blais ◽  
Jay Gambetta ◽  
A. Wallraff ◽  
D. I. Schuster ◽  
S. M. Girvin ◽  
...  
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Electrodynamics ◽  
Quantum Information Processing ◽  
Circuit Quantum Electrodynamics

scholarly journals Single-shot qubit readout in circuit quantum electrodynamics

2009 ◽  
Vol 5 (11) ◽  
pp. 791-795 ◽  
Author(s):  
François Mallet ◽  
Florian R. Ong ◽  
Agustin Palacios-Laloy ◽  
François Nguyen ◽  
Patrice Bertet ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Single Shot ◽  
Circuit Quantum Electrodynamics

scholarly journals Circuit quantum electrodynamics with a spin qubit

Nature ◽  
2012 ◽  
Vol 490 (7420) ◽  
pp. 380-383 ◽  
Author(s):  
K. D. Petersson ◽  
L. W. McFaul ◽  
M. D. Schroer ◽  
M. Jung ◽  
J. M. Taylor ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Circuit Quantum Electrodynamics ◽  
Spin Qubit

Engineering Electronic Structure to Protect Phase Memory in Molecular Qubits by Minimising Orbital Angular Momentum

2018 ◽  
Author(s):  
Ana Maria Ariciu ◽  
David H. Woen ◽  
Daniel N. Huh ◽  
Lydia Nodaraki ◽  
Andreas Kostopoulos ◽  
...  
Keyword(s):  
Electron Spin ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Pulse Sequences ◽  
Grover Algorithm ◽  
Ligand Shell ◽  
Information Strategies ◽  
Spin Qubit ◽  
Molecular Spin ◽  
The Impact

Using electron spins within molecules for quantum information processing (QIP) was first proposed by Leuenberger and Loss (1), who showed how the Grover algorithm could be mapped onto a Mn12 cage (2). Since then several groups have examined two-level (S = ½) molecular spin systems as possible qubits (3-12). There has also been a report of the implementation of the Grover algorithm in a four-level molecular qudit (13). A major challenge is to protect the spin qubit from noise that causes loss of phase information; strategies to minimize the impact of noise on qubits can be categorized as corrective, reductive, or protective. Corrective approaches allow noise and correct for its impact on the qubit using advanced microwave pulse sequences (3). Reductive approaches reduce the noise by minimising the number of nearby nuclear spins (7-11), and increasing the rigidity of molecules to minimise the effect of vibrations (which can cause a fluctuating magnetic field via spin-orbit coupling) (9,11); this is essentially engineering the ligand shell surrounding the electron spin. A protective approach would seek to make the qubit less sensitive to noise: an example of the protective approach is the use of clock transitions to render spin states immune to magnetic fields at first order (12). Here we present a further protective method that would complement reductive and corrective approaches to enhancing quantum coherence in molecular qubits. The target is a molecular spin qubit with an effective 2S ground state: we achieve this with a family of divalent rare-earth molecules that have negligible magnetic anisotropy such that the isotropic nature of the electron spin renders the qubit markedly less sensitive to magnetic noise, allowing coherent spin manipulations even at room temperature. If combined with the other strategies, we believe this could lead to molecular qubits with substantial advantages over competing qubit proposals.<br>

scholarly journals Robust and fast post-processing of single-shot spin qubit detection events with a neural network

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tom Struck ◽  
Javed Lindner ◽  
Arne Hollmann ◽  
Floyd Schauer ◽  
Andreas Schmidbauer ◽  
...  
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Bayesian Inference ◽  
Rabi Oscillation ◽  
Detection Methods ◽  
Measured Signal ◽  
Single Shot ◽  
Post Processing ◽  
Readout Signal ◽  
Spin Qubit

AbstractEstablishing low-error and fast detection methods for qubit readout is crucial for efficient quantum error correction. Here, we test neural networks to classify a collection of single-shot spin detection events, which are the readout signal of our qubit measurements. This readout signal contains a stochastic peak, for which a Bayesian inference filter including Gaussian noise is theoretically optimal. Hence, we benchmark our neural networks trained by various strategies versus this latter algorithm. Training of the network with 106 experimentally recorded single-shot readout traces does not improve the post-processing performance. A network trained by synthetically generated measurement traces performs similar in terms of the detection error and the post-processing speed compared to the Bayesian inference filter. This neural network turns out to be more robust to fluctuations in the signal offset, length and delay as well as in the signal-to-noise ratio. Notably, we find an increase of 7% in the visibility of the Rabi oscillation when we employ a network trained by synthetic readout traces combined with measured signal noise of our setup. Our contribution thus represents an example of the beneficial role which software and hardware implementation of neural networks may play in scalable spin qubit processor architectures.

scholarly journals Two-resonator circuit quantum electrodynamics: Dissipative theory

2010 ◽  
Vol 81 (14) ◽  
Author(s):  
Georg M. Reuther ◽  
David Zueco ◽  
Frank Deppe ◽  
Elisabeth Hoffmann ◽  
Edwin P. Menzel ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Circuit Quantum Electrodynamics

scholarly journals Efficient transfer of an arbitrary qutrit state in circuit quantum electrodynamics

2015 ◽  
Vol 40 (23) ◽  
pp. 5602 ◽  
Author(s):  
Tong Liu ◽  
Shao-Jie Xiong ◽  
Xiao-Zhi Cao ◽  
Qi-Ping Su ◽  
Chui-Ping Yang
Keyword(s):  
Quantum Electrodynamics ◽  
Circuit Quantum Electrodynamics ◽  
Efficient Transfer
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