Spin relaxation in a quantum dot due to Nyquist noise

Marquardt, Florian; Abalmassov, V. A.

doi:10.1103/physrevb.71.165325

Cited by 22 publications

(22 citation statements)

References 21 publications

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“…20͒, and electric-field fluctuations can lead to spin relaxation ͑Khaetskii and Nazarov, 2000, 2001; Woods et al, 2002͒. As we will see, this indirect mechanism is not very efficient, and accordingly very long spin-relaxation times have been observed experimentally ͑Fujisawa et al., 2001bHanson et al, 2003Hanson et al, , 2005Elzerman, Hanson, Willems van Beveren, Witkamp, et al, 2004;Kroutvar et al, 2004;Amasha et al, 2006;Sasaki et al, 2006;Meunier et al, 2007͒. In general, fluctuating electric fields could arise from many sources, including fluctuations in the gate potentials, background charge fluctuations or other electrical noise sources ͑Marquardt and Abalmassov, 2005;Borhani et al, 2006͒. However, as we shall see, it appears that in carefully designed measurement systems, the electric-field fluctuations of these extraneous noise sources is less important than those caused by the phonon bath.…”

Section: Relaxation Via the Phonon Bathmentioning

confidence: 99%

Spins in few-electron quantum dots

et al. 2007

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The canonical example of a quantum-mechanical two-level system is spin. The simplest picture of spin is a magnetic moment pointing up or down. The full quantum properties of spin become apparent in phenomena such as superpositions of spin states, entanglement among spins, and quantum measurements. Many of these phenomena have been observed in experiments performed on ensembles of particles with spin. Only in recent years have systems been realized in which individual electrons can be trapped and their quantum properties can be studied, thus avoiding unnecessary ensemble averaging. This review describes experiments performed with quantum dots, which are nanometer-scale boxes defined in a semiconductor host material. Quantum dots can hold a precise but tunable number of electron spins starting with 0, 1, 2, etc. Electrical contacts can be made for charge transport measurements and electrostatic gates can be used for controlling the dot potential. This system provides virtually full control over individual electrons. This new, enabling technology is stimulating research on individual spins. This review describes the physics of spins in quantum dots containing one or two electrons, from an experimentalist's viewpoint. Various methods for extracting spin properties from experiment are presented, restricted exclusively to electrical measurements. Furthermore, experimental techniques are discussed that allow for ͑1͒ the rotation of an electron spin into a superposition of up and down, ͑2͒ the measurement of the quantum state of an individual spin, and ͑3͒ the control of the interaction between two neighboring spins by the Heisenberg exchange interaction. Finally, the physics of the relevant relaxation and dephasing mechanisms is reviewed and experimental results are compared with theories for spin-orbit and hyperfine interactions. All these subjects are directly relevant for the fields of quantum information processing and spintronics with single spins ͑i.e., single spintronics͒.

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Section: Relaxation Via the Phonon Bathmentioning

confidence: 99%

Spins in few-electron quantum dots

et al. 2007

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“…An exhaustive theoretical investigation of the spin-flip mechanisms has been performed for the related GaAs quantum dot system [4,40,41]. In GaAs quantum dots, all reported spin-orbit related mechanisms exhibit a T 1 ∝ B −ν dependence with ν ≥ 5.…”

Section: B High-field Spin-relaxationmentioning

confidence: 99%

Longitudinal spin relaxation of donor-bound electrons in direct band-gap semiconductors

et al. 2016

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We measure the donor-bound electron longitudinal spin-relaxation time (T1) as a function of magnetic field (B) in three high-purity direct-bandgap semiconductors: GaAs, InP, and CdTe, observing a maximum T1 of 1.4 ms, 0.4 ms and 1.2 ms, respectively. In GaAs and InP at low magnetic field, up to ∼2 T, the spin-relaxation mechanism is strongly density and temperature dependent and is attributed to the random precession of the electron spin in hyperfine fields caused by the lattice nuclear spins. In all three semiconductors at high magnetic field, we observe a power-law dependence T1 ∝ B −ν with 3 ν 4. Our theory predicts that the direct spin-phonon interaction is important in all three materials in this regime in contrast to quantum dot structures. In addition, the "admixture" mechanism caused by Dresselhaus spin-orbit coupling combined with single-phonon processes has a comparable contribution in GaAs. We find excellent agreement between high-field theory and experiment for GaAs and CdTe with no free parameters, however a significant discrepancy exists for InP.

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“…However, this problem has been studied in great detail in Ref. [40], and no major impact on the decoherence time has been found. Even if Nyquist noise were a problem, it could be further reduced by using superconducting gates in lieu of normal metal ones.…”

Section: Spin-qubit Decoherence and Relaxationmentioning

confidence: 99%

Long-Distance Spin-Spin Coupling via Floating Gates

et al. 2012

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The electron spin is a natural two-level system that allows a qubit to be encoded. When localized in a gate-defined quantum dot, the electron spin provides a promising platform for a future functional quantum computer. The essential ingredient of any quantum computer is entanglement-for the case of electronspin qubits considered here-commonly achieved via the exchange interaction. Nevertheless, there is an immense challenge as to how to scale the system up to include many qubits. In this paper, we propose a novel architecture of a large-scale quantum computer based on a realization of long-distance quantum gates between electron spins localized in quantum dots. The crucial ingredients of such a long-distance coupling are floating metallic gates that mediate electrostatic coupling over large distances. We show, both analytically and numerically, that distant electron spins in an array of quantum dots can be coupled selectively, with coupling strengths that are larger than the electron-spin decay and with switching times on the order of nanoseconds.

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Spin relaxation in a quantum dot due to Nyquist noise

Cited by 22 publications

References 21 publications

Spins in few-electron quantum dots

Spins in few-electron quantum dots

Longitudinal spin relaxation of donor-bound electrons in direct band-gap semiconductors

Long-Distance Spin-Spin Coupling via Floating Gates

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