期刊
PHYSICAL REVIEW B
卷 92, 期 16, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.92.161403
关键词
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资金
- National Basic Research Program of China (973 Program) [G2009CB929300]
- National Natural Science Foundation of China [61121491]
- Hong Kong RGC/CRF [CUHK4/CRF/12G]
- European Research Council under the European Community/ERC [279781]
- Engineering and Physical Sciences Research Council (EPSRC) [EP/K025945/1, EP/I035536/2]
- Royal Society
- EPSRC [EP/H025952/1, EP/K025945/1, EP/H025952/2, EP/I035536/2, EP/I035536/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/H025952/1, EP/K025945/1, EP/I035536/2, EP/I035536/1, 1106292, EP/H025952/2] Funding Source: researchfish
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.
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