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 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 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

scholarly journals Quantum interface of an electron and a nuclear ensemble

Science ◽  
2019 ◽  
Vol 364 (6435) ◽  
pp. 62-66 ◽  
Author(s):  
D. A. Gangloff ◽  
G. Éthier-Majcher ◽  
C. Lang ◽  
E. V. Denning ◽  
J. H. Bodey ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Nuclear Spin ◽  
Building Blocks ◽  
Spin Excitation ◽  
Many Body ◽  
Quantum Objects ◽  
All Optical ◽  
Spin Qubit ◽  
Many Body Systems ◽  
Optical Rotations

Coherent excitation of an ensemble of quantum objects underpins quantum many-body phenomena and offers the opportunity to realize a memory that stores quantum information. Thus far, a deterministic and coherent interface between a spin qubit and such an ensemble has remained elusive. In this study, we first used an electron to cool the mesoscopic nuclear spin ensemble of a semiconductor quantum dot to the nuclear sideband–resolved regime. We then implemented an all-optical approach to access individual quantized electronic-nuclear spin transitions. Lastly, we performed coherent optical rotations of a single collective nuclear spin excitation—a spin wave. These results constitute the building blocks of a dedicated local memory per quantum-dot spin qubit and promise a solid-state platform for quantum-state engineering of isolated many-body systems.

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