Driven nonlinear dynamics of two coupled exchange-only qubits

Abstract

Inspired by creation of a fast exchange-only qubit (Medford et al., Phys. Rev. Lett., 111, 050501 (2013)), we develop a theory describing the nonlinear dynamics of two such qubits that are capacitively coupled, when one of them is driven resonantly at a frequency equal to its level splitting. We include conditions of strong driving, where the Rabi frequency is a significant fraction of the level splitting, and we consider situations where the splitting for the second qubit may be the same or different than the first. We demonstrate that coupling between qubits can be detected by reading the response of the second qubit, even when the coupling between them is only of about $1\%$ of their level splittings, and calculate entanglement between qubits. Patterns of nonlinear dynamics of coupled qubits and their entanglement are strongly dependent on the geometry of the system, and the specific mechanism of inter-qubit coupling deeply influences dynamics of both qubits. In particular, we describe the development of irregular dynamics in a two-qubit system, explore approaches for inhibiting it, and demonstrate existence of an optimal range of coupling strength maintaining stability during the operational time.

11 pages, 6 figures; One additional figure with changes to the text about the results. Additional references included

References in corpus (11)

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• Coherent control of a single electron spin with electric fields
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Cited by in corpus (11)

• Semiconductor Spin Qubits
• Three-electron spin qubits
• Entangling distant resonant exchange qubits via circuit quantum electrodynamics
• Coupling of three-spin qubits to their electric environment
• A quadrupolar exchange-only spin qubit
• Robust Two-Qubit Gates for Exchange-Coupled Qubits
• Exact CNOT Gates with a Single Nonlocal Rotation for Quantum-Dot Qubits
• Inverted Singlet-Triplet Qubit Coded on a Two-Electron Double Quantum Dot
• Characterisation of an exchange-based two-qubit gate for resonant exchange qubits
• Nonmonotonic buildup of spin-singlet correlations in a double quantum dot
• Universal control of superexchange in linear triple quantum dots with an empty mediator