Cryogenic photonic link using an extended-InGaAs photodiode and short pulse illumination towards high-fidelity drive of superconducting qubits

TL;DR

This paper demonstrates cryogenic high-speed InGaAs photodiodes for efficient, low-noise control and readout of superconducting qubits, enabling multiplexed photonic links with improved signal-to-noise ratios at cryogenic temperatures.

Contribution

It introduces a cryogenic InGaAs photodiode capable of short pulse detection at 1550 nm, enhancing quantum computing control with multiplexed photonic links.

Findings

High responsivity at 1550 nm at 20 mK

20 dB SNR improvement at 4 K for short pulses

Demonstration of multiplexed microwave pulse generation

Abstract

We investigate short pulse illumination of a high-speed extended-InGaAs photodiode at cryogenic temperatures towards its use in control and readout of superconducting qubits. First, we demonstrate high detector responsivity at 1550 nm illumination at 20 mK, a wavelength band unavailable to cryogenic standard InGaAs detectors due to the temperature-dependent bandgap shift. Second, we demonstrate an improved signal-to-noise ratio (SNR) at the shot noise limit for cryogenic short optical pulse detection when compared to conventional modulated continuous-wave laser detection. At 40 uA of photocurrent and a detector temperature of 4 K, short pulse detection yields an SNR improvement of 20 dB and 3 dB for phase and amplitude quadratures, respectively. Lastly, we discuss how short pulse detection offers a path for signal multiplexing, with a demonstration of simultaneous production of microwave pulses at two different carrier frequencies. Together, these advancements establish a path towards low noise and power efficient multiplexed photonic links for quantum computing with a large number of superconducting qubits.