Continuous variable multimode quantum states via symmetric group velocity matching

Abstract

Configurable and scalable continuous variable (CV) quantum networks for measurement-based quantum information protocols or multipartite quantum communication schemes can be obtained via parametric down conversion (PDC) in non-linear waveguides. In this work, we exploit symmetric group velocity matching (SGVM) to engineer the properties of the squeezed modes of the PDC. We identify type II PDC in a single waveguide as the best suited process, since multiple modes with non-negligible amount of squeezing can be obtained. We explore, for the first time, the waveguide dimensions, usually only set to ensure single-mode guiding, as an additional design parameter ensuring indistinguishability of the signal and idler fields. We investigate here potassium titanyl phosphate (KTP), which offers SGVM at telecommunications wavelengths, but our approach can be applied to any non-linear material and pump wavelength. This work paves the way toward the engineering of future large-scale quantum networks in the CV regime.

A multiplexed synthesizer for non-Gaussian photonic quantum state generation

“…The multimode description that we use complies with realistic implementations of Gaussian state sources, such as, for instance, multimode squeezed vacuum sources [27]. It is now indeed well established that spontaneous parametric down-conversion (SPDC) through three-wave mixing process produces a collection of squeezed vacuum states in separate orthogonal spectral modes {φ k (ω)} k∈N , each with a different squeezing parameter [28,29].…”

Mode-selective single-photon addition to a multimode quantum field

“…Such full diagonalization seems to be out of range of analytical computation. Yet, we show that, under some approximations, one can compute analytically an estimation of the effective number of modes K, defined in equation (13). We first make a Gaussian approximation on the phasematching function, and assume a Gaussian pump spectrum:…”

“…Spectro-temporal mode of light are a versatile resource for quantum information and quantum communication protocols [1][2][3]. In particular ultra-fast light, that can be easily manipulated via femtosecond shaping techniques, has been used for application in both discrete variables and continuous variable (CV) encoding [4][5][6][7][8] In order to exploit the large Hilbert space offered by the frequency mode of femtosecond light sources, the tailoring of the spectral mode structure for quantum state generation and manipulation should be performed [2,5,[9][10][11][12][13][14][15][16].…”

Dispersion-engineered $χ^{(2)}$ nanophotonics: a flexible tool for nonclassical light

“…This case has been used in the design of ultrafast optical parametric amplifiers [37,38], where it is desirable for the phase-mismatch to be a weak function of the pump bandwidth. In the context of quantum optics, ultrafast parametric amplifiers that achieve symmetric walk-off have been studied both as a source of multimode squeezing [39] and as a sources of separable photons. We address the latter case in section 6.…”