scholarly journals Coherent control via weak measurements in P31 single-atom electron and nuclear spin qubits

2018 ◽  
Vol 98 (15) ◽  
Author(s):  
J. T. Muhonen ◽  
J. P. Dehollain ◽  
A. Laucht ◽  
S. Simmons ◽  
R. Kalra ◽  
...  
Keyword(s):  
Nuclear Spin ◽  
Coherent Control ◽  
Single Atom ◽  
Spin Qubits ◽  
Weak Measurements

scholarly journals Controllable freezing of the nuclear spin bath in a single-atom spin qubit

2020 ◽  
Vol 6 (27) ◽  
pp. eaba3442 ◽  
Author(s):  
Mateusz T. Mądzik ◽  
Thaddeus D. Ladd ◽  
Fay E. Hudson ◽  
Kohei M. Itoh ◽  
Alexander M. Jakob ◽  
...  
Keyword(s):  
Electron Spin ◽  
Nuclear Spin ◽  
Quantum Coherence ◽  
Spin Dynamics ◽  
Spin Fluctuations ◽  
Single Atom ◽  
Spin Qubits ◽  
Nuclear Dynamics ◽  
Spin Bath ◽  
Spin Qubit

The quantum coherence and gate fidelity of electron spin qubits in semiconductors are often limited by nuclear spin fluctuations. Enrichment of spin-zero isotopes in silicon markedly improves the dephasing time T2*, which, unexpectedly, can extend two orders of magnitude beyond theoretical expectations. Using a single-atom 31P qubit in enriched 28Si, we show that the abnormally long T2* is due to the freezing of the dynamics of the residual 29Si nuclei, caused by the electron-nuclear hyperfine interaction. Inserting a waiting period when the electron is controllably removed unfreezes the nuclear dynamics and restores the ergodic T2* value. Our conclusions are supported by a nearly parameter-free modeling of the 29Si nuclear spin dynamics, which reveals the degree of backaction provided by the electron spin. This study clarifies the limits of ergodic assumptions in nuclear bath dynamics and provides previously unidentified strategies for maximizing coherence and gate fidelity of spin qubits in semiconductors.

scholarly journals Fundamental limits of electron and nuclear spin qubit lifetimes in an isolated self-assembled quantum dot

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
George Gillard ◽  
Ian M. Griffiths ◽  
Gautham Ragunathan ◽  
Ata Ulhaq ◽  
Callum McEwan ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Operating Conditions ◽  
External Control ◽  
Spin Qubits ◽  
Fundamental Limits ◽  
Trade Offs ◽  
Wide Range ◽  
Spin Qubit

AbstractCombining external control with long spin lifetime and coherence is a key challenge for solid state spin qubits. Tunnel coupling with electron Fermi reservoir provides robust charge state control in semiconductor quantum dots, but results in undesired relaxation of electron and nuclear spins through mechanisms that lack complete understanding. Here, we unravel the contributions of tunnelling-assisted and phonon-assisted spin relaxation mechanisms by systematically adjusting the tunnelling coupling in a wide range, including the limit of an isolated quantum dot. These experiments reveal fundamental limits and trade-offs of quantum dot spin dynamics: while reduced tunnelling can be used to achieve electron spin qubit lifetimes exceeding 1 s, the optical spin initialisation fidelity is reduced below 80%, limited by Auger recombination. Comprehensive understanding of electron-nuclear spin relaxation attained here provides a roadmap for design of the optimal operating conditions in quantum dot spin qubits.

Quantum control of electron and nuclear spin qubits in the solid-state

2006 ◽  
Author(s):  
M. V. Gurudev Dutt ◽  
L. Childress ◽  
E. Togan ◽  
J. M. Taylor ◽  
L. Jiang ◽  
...  
Keyword(s):  
Solid State ◽  
Nuclear Spin ◽  
Quantum Control ◽  
Spin Qubits

scholarly journals Quantifying the quantum gate fidelity of single-atom spin qubits in silicon by randomized benchmarking

2015 ◽  
Vol 27 (15) ◽  
pp. 154205 ◽  
Author(s):  
J T Muhonen ◽  
A Laucht ◽  
S Simmons ◽  
J P Dehollain ◽  
R Kalra ◽  
...  
Keyword(s):  
Quantum Gate ◽  
Single Atom ◽  
Spin Qubits

scholarly journals Effect of electron-nuclear spin interactions for electron-spin qubits localized in InGaAs self-assembled quantum dots

2005 ◽  
Vol 97 (4) ◽  
pp. 043706 ◽  
Author(s):  
Seungwon Lee ◽  
Paul von Allmen ◽  
Fabiano Oyafuso ◽  
Gerhard Klimeck ◽  
K. Birgitta Whaley
Keyword(s):  
Quantum Dots ◽  
Electron Spin ◽  
Nuclear Spin ◽  
Spin Qubits ◽  
Spin Interactions ◽  
Self Assembled

Room temperature coherent control of defect spin qubits in silicon carbide

Nature ◽  
2011 ◽  
Vol 479 (7371) ◽  
pp. 84-87 ◽  
Author(s):  
William F. Koehl ◽  
Bob B. Buckley ◽  
F. Joseph Heremans ◽  
Greg Calusine ◽  
David D. Awschalom
Keyword(s):  
Silicon Carbide ◽  
Room Temperature ◽  
Coherent Control ◽  
Spin Qubits

All-electric control of donor nuclear spin qubits in silicon

2017 ◽  
Vol 12 (10) ◽  
pp. 958-962 ◽  
Author(s):  
Anthony J. Sigillito ◽  
Alexei M. Tyryshkin ◽  
Thomas Schenkel ◽  
Andrew A. Houck ◽  
Stephen A. Lyon
Keyword(s):  
Nuclear Spin ◽  
Spin Qubits ◽  
Electric Control
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