Quantum filtering for multiple measurements driven by fields in single-photon states

In this paper, we derive the stochastic master equations for quantum systems driven by a single-photon input state which is contaminated by quantum vacuum noise. To improve estimation performance, quantum filters based on multiple-channel measurements are designed. Two cases, namely diffusive plus Poissonian measurements and two diffusive measurements, are considered.Comment: 8 pages, 6 figures, submitted for publication. Comments are welcome

Quantum trajectories for propagating Fock states

We derive quantum trajectories (also known as stochastic master equations) that describe an arbitrary quantum system probed by a propagating wave packet of light prepared in a continuous-mode Fock state. We consider three detection schemes of the output light: photon counting, homodyne detection, and heterodyne detection. We generalize to input field states that are superpositions and or mixtures of Fock states and illustrate the formalism with several examples.Comment: 20 pages, 4 figure

Wigner negativity in the steady-state output of a Kerr parametric oscillator

The output field from a continuously driven linear parametric oscillator may exhibit considerably more squeezing than the intracavity field. Inspired by this fact, we explore the nonclassical features of the steady-state output field of a driven nonlinear Kerr parametric oscillator using a temporal wave packet mode description. Utilizing a new numerical method, we have access to the density matrix of arbitrary wave packet modes. Remarkably, we find that even though the steady-state cavity field is always characterized by a positive Wigner function, the output may exhibit Wigner negativity, depending on the properties of the selected mode

Nonclassical light from semiconductor micro- and nanostructures

This thesis studies the quantum properties of light emitted from semiconductor structures. Inside a semiconductor cavity of intermediate coupling, a quantum dot is shown to emit squeezed light, which is robust against dissipation. In a quantum well, the exciton dynamics and the absorption of the medium have to be combined to obtain the emission spectra and reveal nonclassical quantum correlations. The broad emission spectra of semiconductors demand the filtering of the fields before analysis. The influence of filtering on the quantum fields is studied