scholarly journals Embedded quantum-error correction and controlled-phase gate for molecular spin qubits

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025134
Author(s):  
A. Chiesa ◽  
F. Petiziol ◽  
E. Macaluso ◽  
S. Wimberger ◽  
P. Santini ◽  
...  
Keyword(s):  
Error Correction ◽  
Quantum Error Correction ◽  
Spin Qubits ◽  
Phase Gate ◽  
Molecular Spin ◽  
Controlled Phase Gate ◽  
Quantum Error

scholarly journals A Silicon Surface Code Architecture Resilient Against Leakage Errors

Quantum ◽  
2019 ◽  
Vol 3 ◽  
pp. 212 ◽  
Author(s):  
Zhenyu Cai ◽  
Michael A. Fogarty ◽  
Simon Schaal ◽  
Sofia Patomäki ◽  
Simon C. Benjamin ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Error Correction ◽  
Large Scale ◽  
Building Blocks ◽  
Quantum Error Correction ◽  
Error Correction Codes ◽  
Relaxation Processes ◽  
Spin Qubits ◽  
Surface Code ◽  
Quantum Error

Spin qubits in silicon quantum dots are one of the most promising building blocks for large scale quantum computers thanks to their high qubit density and compatibility with the existing semiconductor technologies. High fidelity single-qubit gates exceeding the threshold of error correction codes like the surface code have been demonstrated, while two-qubit gates have reached 98% fidelity and are improving rapidly. However, there are other types of error --- such as charge leakage and propagation --- that may occur in quantum dot arrays and which cannot be corrected by quantum error correction codes, making them potentially damaging even when their probability is small. We propose a surface code architecture for silicon quantum dot spin qubits that is robust against leakage errors by incorporating multi-electron mediator dots. Charge leakage in the qubit dots is transferred to the mediator dots via charge relaxation processes and then removed using charge reservoirs attached to the mediators. A stabiliser-check cycle, optimised for our hardware, then removes the correlations between the residual physical errors. Through simulations we obtain the surface code threshold for the charge leakage errors and show that in our architecture the damage due to charge leakage errors is reduced to a similar level to that of the usual depolarising gate noise. Spin leakage errors in our architecture are constrained to only ancilla qubits and can be removed during quantum error correction via reinitialisations of ancillae, which ensure the robustness of our architecture against spin leakage as well. Our use of an elongated mediator dots creates spaces throughout the quantum dot array for charge reservoirs, measuring devices and control gates, providing the scalability in the design.

scholarly journals 2-designs and redundant syndrome extraction for quantum error correction

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Vickram N. Premakumar ◽  
Hele Sha ◽  
Daniel Crow ◽  
Eric Bach ◽  
Robert Joynt
Keyword(s):  
Error Correction ◽  
Quantum Error Correction ◽  
Quantum Error

scholarly journals Exponential suppression of bit or phase errors with cyclic error correction

Nature ◽  
2021 ◽  
Vol 595 (7867) ◽  
pp. 383-387
Author(s):  
◽  
Zijun Chen ◽  
Kevin J. Satzinger ◽  
Juan Atalaya ◽  
Alexander N. Korotkov ◽  
...  
Keyword(s):  
Error Correction ◽  
Error Detection ◽  
Fault Tolerant ◽  
Error Rates ◽  
Quantum Error Correction ◽  
Superconducting Qubits ◽  
Two Dimensional ◽  
Logical Error ◽  
Quantum Error ◽  
Logical Qubit

AbstractRealizing the potential of quantum computing requires sufficiently low logical error rates1. Many applications call for error rates as low as 10−15 (refs. 2–9), but state-of-the-art quantum platforms typically have physical error rates near 10−3 (refs. 10–14). Quantum error correction15–17 promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected. Errors on the encoded logical qubit state can be exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold and stable over the course of a computation. Here we implement one-dimensional repetition codes embedded in a two-dimensional grid of superconducting qubits that demonstrate exponential suppression of bit-flip or phase-flip errors, reducing logical error per round more than 100-fold when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analysing error correlations with high precision, allowing us to characterize error locality while performing quantum error correction. Finally, we perform error detection with a small logical qubit using the 2D surface code on the same device18,19 and show that the results from both one- and two-dimensional codes agree with numerical simulations that use a simple depolarizing error model. These experimental demonstrations provide a foundation for building a scalable fault-tolerant quantum computer with superconducting qubits.

scholarly journals Impact of correlations and heavy tails on quantum error correction

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
B. D. Clader ◽  
Colin J. Trout ◽  
Jeff P. Barnes ◽  
Kevin Schultz ◽  
Gregory Quiroz ◽  
...  
Keyword(s):  
Error Correction ◽  
Heavy Tails ◽  
Quantum Error Correction ◽  
Quantum Error
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