Nano-Chevron Quantum Dot for All Electrical Spin-Qubit Applications

Nanoscale ◽  
2021 ◽  
Author(s):  
John Tiessen ◽  
Junxia Shi
Keyword(s):  
Quantum Dot ◽  
Spin Qubit ◽  
Electrical Spin

We study the theoretical properties of a parabolic hBN/MoS2/hBN heterostructure quantum dot potential generated via electrostatic gates and its interaction with a Cobalt nano chevron. We demonstrate that such an...

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 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.

scholarly journals Initialization of a spin qubit in a site-controlled nanowire quantum dot

2016 ◽  
Vol 18 (5) ◽  
pp. 053024 ◽  
Author(s):  
Konstantinos G Lagoudakis ◽  
Peter L McMahon ◽  
Kevin A Fischer ◽  
Shruti Puri ◽  
Kai Müller ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Spin Qubit ◽  
A Site

scholarly journals Isotopically enhanced triple-quantum-dot qubit

2015 ◽  
Vol 1 (4) ◽  
pp. e1500214 ◽  
Author(s):  
Kevin Eng ◽  
Thaddeus D. Ladd ◽  
Aaron Smith ◽  
Matthew G. Borselli ◽  
Andrey A. Kiselev ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Coherent Control ◽  
Spin Echo ◽  
Pulse Sequences ◽  
Low Noise ◽  
Single Shot ◽  
Spin Qubit ◽  
Echo Type ◽  
Silicon Based ◽  
Long Pulse

Like modern microprocessors today, future processors of quantum information may be implemented using all-electrical control of silicon-based devices. A semiconductor spin qubit may be controlled without the use of magnetic fields by using three electrons in three tunnel-coupled quantum dots. Triple dots have previously been implemented in GaAs, but this material suffers from intrinsic nuclear magnetic noise. Reduction of this noise is possible by fabricating devices using isotopically purified silicon. We demonstrate universal coherent control of a triple-quantum-dot qubit implemented in an isotopically enhanced Si/SiGe heterostructure. Composite pulses are used to implement spin-echo type sequences, and differential charge sensing enables single-shot state readout. These experiments demonstrate sufficient control with sufficiently low noise to enable the long pulse sequences required for exchange-only two-qubit logic and randomized benchmarking.

Quantum dot spin-photon entanglement and quantum teleportation from a Photon to a Solid-State Spin Qubit

CLEO: 2014 ◽  
2014 ◽  
Author(s):  
W. B. Gao ◽  
P. Fallahi ◽  
E. Togan ◽  
A. Delteil ◽  
Y. S. Chin ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Dot ◽  
Quantum Teleportation ◽  
Spin Qubit ◽  
State Spin
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