X-States of a Qubit Pair of Double Classicality

Manu Pratap Singh, B. S. Rajput

A. Khvedelidze, Dimitar M. Mladenov, Astghik Torosyan

A special class of states of 2-qubits which are simultaneously separable and have positive semidefinite Wigner functions is described.

G.V. Klimovitch

Classical feedback is defined here as the knowledge by the transmitter of the quantum state of the qubit received by the receiver. Such classical feedback doubles capacities of certain memoryless quantum channels without preexisting entanglement between transmitter and receiver. The increase in capacity, which is absent on classical memoryless channels, occurs because we can transform an entangled qubit pair into any other entangled state by applying a unitary operator to only one of the qubits.

Paulo E. M. F. Mendonça, Marcelo A. Marchiolli, D. Galetti

Andrey E. Schegolev, N. V. Klenov, Anna V. Bogatskaya +2 more

We have determined conditions when a pair of coupled waveguides, a common element for integrated room-temperature photonics, can act as a qubit based on a system with a double-well potential. Moreover, we have used slow-varying amplitude approximation (SVA) for the "classical" wave equation to study the propagation of electromagnetic beams in a couple of dielectric waveguides both analytically and numerically. As a part of an extension of the optical-mechanical analogy, we have considered examples of "quantum operations" on the electromagnetic wave state in a pair of waveguides. Furthermore, we have provided examples of "quantum-mechanical" calculations of nonlinear transfer functions for the implementation of the considered element in optical neural networks.

Josep Amengual i Batle, C. H. Raymond Ooi, Ahmed Farouk +1 more