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arXiv · 2108.01206

Coherent spin-spin coupling mediated by virtual microwave photons

Patrick Harvey-Collard·Jurgen Dijkema·Guoji Zheng·Amir Sammak·Giordano Scappucci·Lieven M. K. Vandersypen
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Abstract

We report the coherent coupling of two electron spins at a distance via virtual microwave photons. Each spin is trapped in a silicon double quantum dot at either end of a superconducting resonator, achieving spin-photon couplings up to around $g_s/2\pi = 40 \ \text{MHz}$. As the two spins are brought into resonance with each other, but detuned from the photons, an avoided crossing larger than the spin linewidths is observed with an exchange splitting around $2J/2\pi = 20 \ \text{MHz}$. In addition, photon-number states are resolved from the shift $2\chi_s/2\pi = -13 \ \text{MHz}$ that they induce on the spin frequency. These observations demonstrate that we reach the strong dispersive regime of circuit quantum electrodynamics with spins. Achieving spin-spin coupling without real photons is essential to long-range two-qubit gates between spin qubits and scalable networks of spin qubits on a chip.

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Patrick Harvey-Collard, Jurgen Dijkema, Guoji Zheng, Amir Sammak, Giordano Scappucci, Lieven M. K. Vandersypen. 2021-08-02. Coherent spin-spin coupling mediated by virtual microwave photons. https://doi.org/10.1103/physrevx.12.021026

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