Generators of nonclassical states by a combination of linear coupling of boson modes, Kerr nonlinearity, and strong linear losses

Abstract

We show that the generators of quantum states of light can be built by employing the Kerr nonlinearity, a strong linear absorption or losses and the linear coupling of optical modes. Our setup can be realized, for instance, with the use of the optical fiber technology. We consider in detail the simplest cases of three and four coupled modes, where a strongly lossy mode is linearly coupled to other linear and nonlinear modes. In the three-mode design, our scheme emulates the third-order nonlinear absorption, allowing for generation of the single photon states, or the twophoton absorption allowing to generate the phase states. In the four-mode design, the scheme emulates a non-local absorption which produces an entangled state of two uncoupled modes. We also note that in the latter case and in the case of the phase states generation the output state is in the linear modes, which prevents its subsequent degradation by strong losses accompanying a strong Kerr nonlinearity.

Coherent Diffusive Photon Gun for Generating Nonclassical States

“…The basic idea underlying our scheme is to create a photonic circuit exhibiting nonlinear coherent loss (NCL), which is a specific kind of engineered singlephoton loss with the decay rate dependent on the number of photons [24,25]. The principal circuit, Fig.…”

State engineering for a Bose-Einstein condensate in an optical lattice by means of a periodic sublattice of dissipative sites

“…In our approximation, given by Eqs. (12) and (17), we have U a † a /J ≪ 1. Thus one can keep only the degenerate modes in the nonlinear term, which we denote as ϕ + ≡ ϕ 0,0,1 and ϕ − ≡ ϕ 0,0,2 .…”

“…By performing the adiabatic elimination of the dissipative sites (a n,0 ) (for the details, consult Ref. [12], section II) the master equation is reduced to that for the nondissipative sites only (with the reduced density matrix ρ R ), which is in the same form as Eq. (2) with, however, a reduced dissipation rate γ and a reduced Hamiltonian H R (the terms depending on the operators of the dissipative sites are thrown away).…”

“…Skipping the details (see Ref. [12], section II), let us write down the resulting reduced master equation for the density matrix ρ R describing the non-dissipative sites…”

“…It is shown below that the condensate is driven to a coherent non-local Bloch-like state described by a complex-valued order parameter (in the two-dimensional case) or the order parameter with nodes (in the one-dimensional case). This is achieved by the emulation of a coherent non-local dissipation by a local one, similar as in the recently proposed scheme for generators of the non-classical states of photons [11,12].…”