Coherent spin-photon coupling is believed to play a significant role in silicon-based quantum computation. The resonant exchange (RX) qubit, formed in a triple quantum dot, is a promising platform for spin-photon coupling and qubit scaling due to the large electric dipole moment and full electrical control without auxiliary micromagnets. However, there has been no experimental demonstration of silicon RX qubits and their strong coupling to microwave photons to date. In this work, we report the strong coupling between an RX qubit and a high-impedance resonator on a Si/SiGe heterostructure with coupling strength g_{s}/(2π)=65.8 MHz and decoherence rate γ_{s}/(2π)=21.4 MHz. Furthermore, the dependence of decoherence rate on detuning is measured and analyzed using a phenomenological model, indicating that the charge noise is the main source of decoherence. Our results demonstrate the viability of RX qubits in silicon, highlighting their crucial role of large-scale qubit integration for silicon quantum computation and opening new possibilities for quantum network.
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
gs/2π=40MHz. 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/2π=20MHz. In addition, photon number states are resolved from the shift
2χs/2π=−13MHz they induce on the spin frequency. These results could enable long-range two-qubit gates between spin qubits and scalable networks of spin qubits on a chip.
Spin qubits and superconducting qubits are among the promising candidates for realizing a solid state quantum computer. For the implementation of a hybrid architecture which can profit from the advantages of either approach, a coherent link is necessary that integrates and controllably couples both qubit types on the same chip over a distance that is several orders of magnitude longer than the physical size of the spin qubit. We realize such a link with a frequency-tunable high impedance SQUID array resonator. The spin qubit is a resonant exchange qubit hosted in a GaAs triple quantum dot. It can be operated at zero magnetic field, allowing it to coexist with superconducting qubits on the same chip. We spectroscopically observe coherent interaction between the resonant exchange qubit and a transmon qubit in both resonant and dispersive regimes, where the interaction is mediated either by real or virtual resonator photons.