Suppressing qubit dephasing using real-time Hamiltonian estimation

Abstract

Unwanted interaction between a quantum system and its fluctuating environment leads to decoherence and is the primary obstacle to establishing a scalable quantum information processing architecture. Strategies such as environmental and materials engineering, quantum error correction and dynamical decoupling can mitigate decoherence, but generally increase experimental complexity. Here we improve coherence in a qubit using real-time Hamiltonian parameter estimation. Using a rapidly converging Bayesian approach, we precisely measure the splitting in a singlet-triplet spin qubit faster than the surrounding nuclear bath fluctuates. We continuously adjust qubit control parameters based on this information, thereby improving the inhomogenously broadened coherence time ($T_2^{\ast }$) from tens of nanoseconds to above 2 $\mu$s and demonstrating the effectiveness of Hamiltonian estimation in reducing the effects of correlated noise in quantum systems. Because the technique demonstrated here is compatible with arbitrary qubit operations, it is a natural complement to quantum error correction and can be used to improve the performance of a wide variety of qubits in both metrological and quantum-information-processing applications.

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Cited by in corpus (10)

• Accelerated Randomized Benchmarking
• Quantum Bootstrapping via Compressed Quantum Hamiltonian Learning
• Environmental noise effects on entanglement fidelity of exchange-coupled semiconductor spin qubits
• Fault-Tolerant Quantum Computation for Singlet-Triplet Qubits with Leakage Errors
• Dynamics of entanglement of two electron spins interacting with nuclear spin baths in quantum dots
• Soft Decoding of a Qubit Readout Apparatus
• High Fidelity Singlet-Triplet $S$-$T_{-}$ Qubits in Inhomogeneous Magnetic Fields
• Inverted Singlet-Triplet Qubit Coded on a Two-Electron Double Quantum Dot
• Theory of box-model hyperfine couplings and transport signatures of long-range nuclear-spin coherence in a quantum-dot spin valve
• Coulomb-blockade and Pauli-blockade magnetometry