New method for improving squeezed light generation involving pump fluctuations

Kazuki Hirota, Takahiro Kashiwazaki, Gyeongmin Ha +10 more

We report generation of 10.1\pm0.2-dB squeezed light from a broadband periodically poled lithium niobate (PPLN) waveguide optical parametric amplifier (OPA). Based on our previous report where a similar PPLN waveguide shows 8.3-dB squeezing [T. Kashiwazaki et al., Appl. Phys. Lett. 122, 234003 (2023)], we reduce phase fluctuations and overall optical losses in the measurement system. In particular, we introduce a novel phase detection technique that does not require tapping a part of the squeezed light to get a phase locking signal. We use a phase-detection OPA seeded by a tapped probe and pump light before a squeezer OPA. This configuration breaks the conventional trade-off between generating a phase-locking signal with high-signal-to-noise ratio and suppressing degradation of squeezing level caused by optical tapping. With all these improvements, the phase fluctuation angle is reduced from 14 mrad to 9 mrad, and the total optical loss from 12\% to 8\%. Achieving more than 10 dB of squeezing by the broadband waveguide OPA is a significant step towards realization of fault-tolerant ultra-fast universal optical quantum computation.

M. D. Reid, Alistair S. Lane, Daniel F. Walls

Daniel F. Walls, Gerard J Milburn

Jun Zhou

A new method has been developed for pulse squeezed light generation in parametric process by using low repetition pulse laser. With this new technique, it becomes very easy to realize the condition for obtaining substantial squeezing, i. e. the damping constant for pump field should be much smaller than that for the parametric signal field. This condition, however, was difficult to be realized with conventional experimental setup by using low repetition pulse laser. Semiclassical approach indicates that deep degree squeezing may be obtained over a wide frequency range by increasing the ratio of the dumping constant for signal field to that for the pump field in the new experimental setup. At the same time, the conversion efficiency of the second-harmonic generation can also be increased remarkably by this new method in the squeezed light generation process.

Daniel F. Walls, Gerard J Milburn

Ruijian Wang

Squeezed light, a non-classical state characterized by reduced quantum fluctuations in one field quadrature, is a key resource for improving precision measurements and quantum metrology. In the past decades, the most well-known application of squeezed light is in gravitational wave detection, realized by the Laser Interferometer Gravitational- Wave Observatory (LIGO). There, squeezing has pushed the strain precision of a 4-km-long interferometer to an astounding level below 10−23 1/√Hz. An interesting question we are pursuing is whether squeezing and related improvements in precision can be realized in cm-size photonic chips. Recently, the Kerr nonlinearity on integrated photonics chips has opened a new window for squeezed light generation in a nanophotonic platform. In this thesis, we seek to extend these advances to single-mode squeezed state (SMS) generation in Silicon Nitride (SiN) Fabry-Perot Bragg Grating (FPBG) microresonators with a coherent-laser-based dual-pump SMS scheme. This is the first step towards a robust and scalable approach of on-chip squeezed-light sources for a new class of integrated photonics sensors.