Ma, W-L;
Wolfowicz, G;
Li, S-S;
Morton, JJL;
Liu, R-B;
(2015)
Classical nature of nuclear spin noise near clock transitions of Bi donors in silicon.
PHYSICAL REVIEW B
, 92
, Article 161403(R). 10.1103/PhysRevB.92.161403.
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Abstract
Whether a quantum bath can be approximated as classical Gaussian noise is a fundamental issue in central spin decoherence and also of practical importance in designing noise-resilient quantum control. Spin qubits based on bismuth donors in silicon have tunable interactions with nuclear spin baths and are first-order insensitive to magnetic noise at so-called clock transitions (CTs). This system is therefore ideal for studying the quantum/classical Gaussian nature of nuclear spin baths since the qubit-bath interaction strength determines the back-action on the baths and hence the adequacy of a Gaussian noise model. We develop a Gaussian noise model with noise correlations determined by quantum calculations and compare the classical noise approximation to the full quantum bath theory. We experimentally test our model through a dynamical decoupling sequence of up to 128 pulses, finding good agreement with simulations and measuring electron spin coherence times approaching 1 s—notably using natural silicon. Our theoretical and experimental study demonstrates that the noise from a nuclear spin bath is analogous to classical Gaussian noise if the back-action of the qubit on the bath is small compared to the internal bath dynamics, as is the case close to CTs. However, far from the CTs, the back-action of the central spin on the bath is such that the quantum model is required to accurately model spin decoherence.
| Type: | Article |
|---|---|
| Title: | Classical nature of nuclear spin noise near clock transitions of Bi donors in silicon |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevB.92.161403 |
| Publisher version: | http://dx.doi.org/10.1103/PhysRevB.92.161403 |
| Language: | English |
| Additional information: | ©2015 American Physical Society |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1474850 |
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