Abstract
Nonlinear SU(1,1) interferometers are fruitful and promising tools for spectral engineering and precise measurements with phase sensitivity below the classical bound. Such interferometers have been successfully realized in bulk and fiber-based configurations. However, rapidly developing integrated technologies provide higher efficiencies, smaller footprints, and pave the way to quantum-enhanced on-chip interferometry. In this work, we theoretically realised an integrated architecture of the multimode SU(1,1) interferometer which can be applied to various integrated platforms. The presented interferometer includes a polarization converter between two photon sources and utilizes a continuous-wave (CW) pump. Based on the potassium titanyl phosphate (KTP) platform, we show that this configuration results in almost perfect destructive interference at the output and supersensitivity regions below the classical limit. In addition, we discuss the fundamental difference between single-mode and highly multimode SU(1,1) interferometers in the properties of phase sensitivity and its limits. Finally, we explore how to improve the phase sensitivity by filtering the output radiation and using different seeding states in different modes with various detection strategies.
Highlights
One of the main tasks in Quantum Metrology research is to improve both methods and techniques to estimate the phase sensitivity of interferometers [1]
The nonlinear SU(1,1) interferometers can beat the shot noise limit (SNL) even without using quantum states as inputs [8]. This type of interferometer consists of two nonlinear processes [9], such as four-wave-mixing (FWM) or parametric downconversion (PDC)
We investigate the spectral properties of the monolithic SU(1,1) interferometer based on the potassium titanyl phosphate (KTP) platform and demonstrate conditions for obtaining the phase sensitivity below the shot noise limit
Summary
One of the main tasks in Quantum Metrology research is to improve both methods and techniques to estimate the phase sensitivity of interferometers [1]. The phase sensitivity of this class of interferometers has been investigated for spectrally single-mode sources [12, 13, 14], including gainunbalanced [15, 16] and fully quantum threemode [17] configurations, as well as configurations with different input states, such as coherent light [18], squeezed states [19], a mixture of coherent and squeezing states [20, 21, 22] and a mixture of thermal and squeezed states [23] These studies have shown that it is generally possible to overcome the shot noise limit and even reach the Heisenberg limit. We extend the analysis by considering non-vacuum input states along with different detection strategies, i.e. direct detection and homodyne detection
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