Abstract
Quantum computing offers the potential to solve complex problems beyond the reach of classical systems, with applications in cryptography, optimization, and scientific simulation. Photonic continuous-variable (CV) quantum computing harnesses light’s properties to enable scalable, fault-tolerant quantum computation. This dissertation contributes to this field through developing high performing optical parametric oscillators (OPOs) and photon-number-resolving detectors (PNRDs). These efforts improve the generation and detection of quantum states, providing practical tools for quantum information processing.
I built two triply resonant optical parametric oscillators—a nondegenerate design which demonstrated 6 dB gain and a degenerate one achieving 24 dB gain—demonstrating strong potential for record quantum squeezing as the squeezing record is 15dB. These OPOs are sources of two-mode squeezed states, entangled photon pairs, and CV cluster states, supporting measurement based quantum computing (MBQC) and related applications. As for PNRDs, I significantly enhanced the photon number resolution of the superconducting transition edge sensor (TES) system in our lab, increasing it from 8 to 37 photons per channel, enabling the resolution of up to 100 photons setting a new record up from the previous record of 16. I also modeled segmented detectors using single avalanche photodiodes, offering additional design insights.
PNR detectors enable numerous applications, two of which I explore in this dissertation: a quantum random number generator which I experimentally demonstrated and Fock state interferometry, which I theoretically modeled including losses, validating its use for phase discrimination.
Together, the high-gain OPOs and refined TES bolster photonic CV quantum computing, by paving the way for cubic phase gate realization and by extension universal CV quantum computing.
