Probing spins with cryogenic frequency converters based on high kinetic inductance superconducting transmission lines

Quantum computing architectures utilizing microwave control lines[1] require significant cooling power that can limit the scaling of the system. There has been a push towards developing low-thermal-conductivity, densely-packed superconducting wiring. Alternatively, there has been work towards generating microwave control pulses at cryogenic temperatures by downconverting optical pulses [2]. Here, we present an alternative approach, where a single microwave local oscillator (LO) can be modulated using nonlinear effects in high-kinetic-inductance[3] superconducting circuits to generate control sidebands. In this talk we describe a device capable of generating microwave sidebands with conversion frequencies exceeding GHz. We use this device to probe a superconducting resonator coupled to an electron spin ensemble in a DPPH crystal. We sweep magnetic field and observe a characteristic avoided level crossing in the system utilizing cryogenically-generated microwave tones. Because we have full control over the amplitude and phase of the generated sidebands, this architecture offers a path towards controlling arrays of frequency multiplexed spin qubits at low temperature.

[1] Yoneda, J., Takeda, K., Otsuka, T., Nakajima, T., Delbecq, M. R., Allison, G., ... & Tarucha, S. (2018). A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%. Nature nanotechnology, 13(2), 102-106.

[2] Lecocq, F., Aumentado, J., Diddams, S. A., Quinlan, F. J., & Teufel, J. D. (2020, September). Control and readout of a superconducting qubit using a cryogenic photonic link. In Quantum 2.0 (pp. QM6A-3). Optica Publishing Group.

[3] Annunziata, A. J. (2010). Single-photon detection, kinetic inductance, and non-equilibrium dynamics in niobium and niobium nitride superconducting nanowires. Yale University.