Integrated quantum optical phase sensor in thin film lithium niobate

The quantum noise of light, attributed to the random arrival time of photons from a coherent light source, fundamentally limits optical phase sensors. An engineered source of squeezed states suppresses this noise and allows phase detection sensitivity beyond the quantum noise limit (QNL). We need ways to use quantum light within deployable quantum sensors. Here we present a photonic integrated circuit in thin-film lithium niobate that meets these requirements. We use the second-order nonlinearity to produce a squeezed state at the same frequency as the pump light and realize circuit control and sensing with electro-optics. Using 26.2 milliwatts of optical power, we measure (2.7 +/- 0.2)% squeezing and apply it to increase the signal-to-noise ratio of phase measurement. We anticipate that photonic systems like this, which operate with low power and integrate all of the needed functionality on a single die, will open new opportunities for quantum optical sensing.

Automated summary

The research focuses on the limitation of optical phase sensors due to the quantum noise of light. To overcome this, an engineered source of squeezed states is introduced to suppress the noise and improve the phase detection sensitivity. A photonic integrated circuit in thin-film lithium niobate is designed and used to generate squeezed states with the same frequency as the pump light, allowing for circuit control and sensing with electro-optics. The results show (2.7 +/- 0.2)% squeezing when using 26.2 milliwatts of optical power, and it is applied to increase the signal-to-noise ratio of phase measurement. Such low-power and integrated photonic systems have great potential in advancing quantum optical sensing.