Search results for "Coherent state"
showing 10 items of 95 documents
An application of the arithmetic euler function to the construction of nonclassical states of a quantum harmonic oscillator
2001
Abstract All quantum superpositions of two equal intensity coherent states exhibiting infinitely many zeros in their Fock distributions are explicitly constructed and studied. Our approach is based on results from number theory and, in particular, on the properties of arithmetic Euler function. The nonclassical nature of these states is briefly pointed out. Some interesting properties are brought to light.
Quantum pattern recognition in photonic circuits
2021
This paper proposes a machine learning method to characterize photonic states via a simple optical circuit and data processing of photon number distributions, such as photonic patterns. The input states consist of two coherent states used as references and a two-mode unknown state to be studied. We successfully trained supervised learning algorithms that can predict the degree of entanglement in the two-mode state as well as perform the full tomography of one photonic mode, obtaining satisfactory values in the considered regression metrics.
Tunable non-Gaussian resources for continuous-variable quantum technologies
2013
We introduce and discuss a set of tunable two-mode states of continuous-variable systems, as well as an efficient scheme for their experimental generation. This novel class of tunable entangled resources is defined by a general ansatz depending on two experimentally adjustable parameters. It is very ample and flexible as it encompasses Gaussian as well as non-Gaussian states. The latter include, among others, known states such as squeezed number states and de-Gaussified photon-added and photon-subtracted squeezed states, the latter being the most efficient non-Gaussian resources currently available in the laboratory. Moreover, it contains the classes of squeezed Bell states and even more ge…
D-Pseudo-Bosons, Complex Hermite Polynomials, and Integral Quantization
2015
The D-pseudo-boson formalism is illustrated with two examples. The first one involves deformed complex Hermite polynomials built using finite-dimensional irreducible representations of the group GL(2, C) of invertible 2 × 2 matrices with complex entries. It reveals interesting aspects of these representations. The second example is based on a pseudo-bosonic generalization of operator-valued functions of a complex variable which resolves the identity. We show that such a generalization allows one to obtain a quantum pseudo-bosonic version of the complex plane viewed as the canonical phase space and to understand functions of the pseudo-bosonic operators as the quantized versions of functions…
Continuous-variable entanglement sharing in noninertial frames
2007
We study the distribution of entanglement between modes of a free scalar field from the perspective of observers in uniform acceleration. We consider a two-mode squeezed state of the field from an inertial perspective, and analytically study the degradation of entanglement due to the Unruh effect, in the cases of either one or both observers undergoing uniform acceleration. We find that for two observers undergoing finite acceleration, the entanglement vanishes between the lowest frequency modes. The loss of entanglement is precisely explained as a redistribution of the inertial entanglement into multipartite quantum correlations among accessible and unaccessible modes from a non-inertial p…
Bicoherent-State Path Integral Quantization of a non-Hermitian Hamiltonian
2020
We introduce, for the first time, bicoherent-state path integration as a method for quantizing non-hermitian systems. Bicoherent-state path integrals arise as a natural generalization of ordinary coherent-state path integrals, familiar from hermitian quantum physics. We do all this by working out a concrete example, namely, computation of the propagator of a certain quasi-hermitian variant of Swanson's model, which is not invariant under conventional $PT$-transformation. The resulting propagator coincides with that of the propagator of the standard harmonic oscillator, which is isospectral with the model under consideration by virtue of a similarity transformation relating the corresponding…
Coherence absorption and condensation induced by thermalization of incoherent nonlinear fields
2008
We show that a conservative system of incoherent nonlinear waves exhibits, as a rule, an irreversible process of coherence transfer, in which the incoherence of the system is absorbed by the small-amplitude field, thus allowing the high-amplitude field to evolve towards a highly condensed coherent state. This process of coherence absorption results from the natural thermalization of the fields to a thermodynamic equilibrium state. The theory reveals that, contrary to a classical gas system, a wave system does not satisfy an equipartition of energy among the particles. Such a distinctive feature is the key property underlying the existence of the coherence absorption process. The coherence a…
On-chip quantum optical frequency comb sources
2018
Integrated optical frequency comb sources, based on nonlinear microring resonators, can be used to generate complex quantum states. In particular, we achieved multi-photon and high-dimensional entangled quantum states, as well as their coherent control.
Accelerated stabilization of coherent photon states
2018
| openaire: EC/H2020/681311/EU//QUESS Control and utilization of coherent states of microwave photons is a ubiquitous requirement for the present and near-future implementations of solid-state quantum computers. The rate at which the photon state responds to external driving is limited by the relaxation rate of the storage resonator, which poses a trade-off between fast control and long storage time. Here, we present a control scheme that is designed to drive an unknown photon state to a desired coherent state much faster than the resonator decay rate. Our method utilizes a tunable environment which acts on an ancillary qubit coupled to the resonator. By periodically resetting the qubit and…
Finite-temperature correlations in the trapped Bose-Einstein gas
2001
There is a large literature (cf. eg. [1, 2]) which, under conditions of translational invariance, has used functional integral methods to calculate, ab initio, the equilibrium finite temperature 2-point correlation functions (Green ’s functions) \[\left\langle {\hat \psi (r,\tau ){{\hat \psi }^\dag }(r',\tau ')} \right\rangle \] \(G\left( {r,r'} \right) \equiv \left\langle {\psi \left( {r,\tau } \right){{{\hat{\psi }}}^{\dag }}\left( {r',\tau '} \right)} \right\rangle \) for a Bose gas in each of d=3, d=2, d=1 space dimensions: (…) means thermal average and τ, τ′ are ‘thermal times’ for which 0<τ,<τ′β and β−1=k B T, T the temperature. These functional integral methods [1, 2] solve the many-…