EOM Minimum Point Bias Voltage Estimation for Application in Quantum Computing

TL;DR

This paper proposes a method to estimate the bias voltage of electro-optic modulators in quantum computing systems using a pilot tone, aiming to improve modulation accuracy by tracking bias drift.

Contribution

It introduces a novel bias voltage estimation technique based on optical power feedback, enhancing EOM control in quantum computing applications.

Findings

Effective bias voltage estimation using pilot tone demonstrated.

Improved modulation stability in quantum computing systems.

Reduced error rates in quantum state manipulation.

Abstract

In quantum computing systems the quantum states of qubits can be modified among others by applying light pulses. In order to achieve low computing error rates these pulses have to be precisely shaped in magnitude and phase. In practical applications, both acousto-optic (AOM) and electro-optic modulators (EOM) are used for this purpose. The advantages of EOMs, in particular Mach-Zehnder modulators (MZMs), include e.g. higher bandwidth, compactness, good integrability and better noise performance. On the other hand, EOMs are challenging regarding their control voltage regulation as they experience a bias drift, i.e. voltage shifts in the modulator's operating point. Such a shift significantly impairs the quality of the modulation, which is why EOMs usually require a bias control loop to track the DC operating point. This work addresses the estimation of the instantaneous bias voltage using a small pilot tone, where the optical output power of the EOM is tracked by a photodetector feedback signal.