scholarly journals Indications of a soft cutoff frequency in the charge noise of a Si/SiGe quantum dot spin qubit

2019 ◽  
Vol 99 (8) ◽  
Author(s):  
Utkan Güngördü ◽  
J. P. Kestner
Keyword(s):  
Quantum Dot ◽  
Cutoff Frequency ◽  
Spin Qubit ◽  
Sige Quantum Dot ◽  
Charge Noise

scholarly journals Second-Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot

2015 ◽  
Vol 115 (10) ◽  
Author(s):  
P. Scarlino ◽  
E. Kawakami ◽  
D. R. Ward ◽  
D. E. Savage ◽  
M. G. Lagally ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Second Harmonic ◽  
Spin Qubit ◽  
Sige Quantum Dot

scholarly journals A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%

2017 ◽  
Vol 13 (2) ◽  
pp. 102-106 ◽  
Author(s):  
Jun Yoneda ◽  
Kenta Takeda ◽  
Tomohiro Otsuka ◽  
Takashi Nakajima ◽  
Matthieu R. Delbecq ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Spin Qubit ◽  
Charge Noise

scholarly journals Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot

2014 ◽  
Vol 9 (9) ◽  
pp. 666-670 ◽  
Author(s):  
E. Kawakami ◽  
P. Scarlino ◽  
D. R. Ward ◽  
F. R. Braakman ◽  
D. E. Savage ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Electrical Control ◽  
Spin Qubit ◽  
Sige Quantum Dot

scholarly journals Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet

2016 ◽  
Vol 113 (42) ◽  
pp. 11738-11743 ◽  
Author(s):  
Erika Kawakami ◽  
Thibaut Jullien ◽  
Pasquale Scarlino ◽  
Daniel R. Ward ◽  
Donald E. Savage ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Electron Spin ◽  
Quantum Information Processing ◽  
Coherence Time ◽  
Nuclear Spins ◽  
Quantum Bit ◽  
Sige Quantum Dot ◽  
Qubit Gate ◽  
And Control ◽  
Charge Noise

The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ∼99% using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in the substrate. The coherence time measured using dynamical decoupling extends up to ∼400 μs for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10-kHz to 1-MHz range, possibly because charge noise affects the spin via the micromagnet gradient. This work shows that an electron spin in an Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.

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.

scholarly journals Dynamics of Entanglement between a Quantum Dot Spin Qubit and a Photon Qubit inside a Semiconductor High-Q Nanocavity

2010 ◽  
Vol 2010 ◽  
pp. 1-31 ◽  
Author(s):  
Hubert Pascal Seigneur ◽  
Gabriel Gonzalez ◽  
Michael Niklaus Leuenberger ◽  
Winston Vaughan Schoenfeld
Keyword(s):  
Quantum Dot ◽  
Single Photon ◽  
Hyperfine Interactions ◽  
Interaction Time ◽  
Network Node ◽  
Quantum Network ◽  
Entanglement Dynamics ◽  
High Q ◽  
Spin Qubit

We investigate in this paper the dynamics of entanglement between a QD spin qubit and a single photon qubit inside a quantum network node, as well as its robustness against various decoherence processes. First, the entanglement dynamics is considered without decoherence. In the small detuning regime (Δ=78 μeV), there are three different conditions for maximum entanglement, which occur after 71, 93, and 116 picoseconds of interaction time. In the large detuning regime (Δ=1.5 meV), there is only one peak for maximum entanglement occurring at 625 picoseconds. Second, the entanglement dynamics is considered with decoherence by including the effects of spin-nucleus and hole-nucleus hyperfine interactions. In the small detuning regime, a decent amount of entanglement (35% entanglement) can only be obtained within 200 picoseconds of interaction. Afterward, all entanglement is lost. In the large detuning regime, a smaller amount of entanglement is realized, namely, 25%. And, it lasts only within the first 300 picoseconds.

scholarly journals Coplanar and grazing incidence x-ray-diffraction investigation of self-organized SiGe quantum dot multilayers

1998 ◽  
Vol 58 (12) ◽  
pp. 7934-7943 ◽  
Author(s):  
V. Holý ◽  
A. A. Darhuber ◽  
J. Stangl ◽  
S. Zerlauth ◽  
F. Schäffler ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Organized ◽  
Sige Quantum Dot

scholarly journals Three-stage decoherence dynamics of an electron spin qubit in an optically active quantum dot

2015 ◽  
Vol 11 (12) ◽  
pp. 1005-1008 ◽  
Author(s):  
Alexander Bechtold ◽  
Dominik Rauch ◽  
Fuxiang Li ◽  
Tobias Simmet ◽  
Per-Lennart Ardelt ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Electron Spin ◽  
Optically Active ◽  
Spin Qubit
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