We investigate coherent and squeezed quantum states of phonons. The latter allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of coherent states. The expectation values and quantum fluctuations of both the atomic displacement and the lattice amplitude operators are calculated in these states—in some cases analytically. W...

In this article, the quantum correlation measurement technique as a method of power noise monitoring is investigated. Its principal idea correlating two photodetector signals introduced and contrasted to conventional approach, which uses only single photodetector. We discuss how scheme can be used obtain information below shot detected beam also electronic dark individual photodetectors, both n...

Quantum systems of interest are typically coupled to several quantum channels (more generally environments). In this paper, we develop an exact stochastic Schrödinger equation for an open quantum system coupled to a hybrid environment containing both bosonic and fermionic particles. Such a stochastic differential equation may be obtained directly from a microscopic model through employing a cla...

Quantum key distribution enables two remote parties to grow a shared key, which they can use for unconditionally secure communication over a certain distance. The maximal distance depends on the loss and the excess noise of the connecting quantum channel. Several quantum key distribution schemes based on coherent states and continuous variable measurements are resilient to high loss in the chan...

The quantum-classical hybrid algorithm is a promising with respect to demonstrating the quantum advantage in noisy-intermediate-scale (NISQ) devices. When running such algorithms, effects due noise are inevitable. In our work, we consider well-known algorithm, approximate optimization (QAOA). We study on QAOA from typical channels, and produce several numerical results. Our research indicates t...

Grover's quantum algorithm improves any classical search algorithm. We show how random Gaussian noise at each step of the algorithm can be modelled easily because of the exact recursion formulas available for computing the quantum amplitude in Grover's algorithm. We study the algorithm's intrinsic robustess when no quantum correction codes are used, and evaluate how much noise the algorithm can...

We predict phase-transitions in the quantum noise characteristics of systems described by the quantum nonlinear Schrödinger equation, showing them to be related to the solitonic field transition at half the fundamental soliton amplitude. These phase-transitions are robust with respect to Raman noise and scattering losses. We also describe the rich internal quantum noise structure of the soliton...