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David M. Whittaker

Publications and source records attributed to David M. Whittaker.

8 recordsLinked to original sources
arXiv2019

Conservation of Quantum Correlations in Multimode Systems with $U(1)$ Symmetry

We present a theoretical investigation of the properties of quantum correlation functions in a dissipative multimode system. We define a total mth order equal-time correlation function, summed over all modes, which is shown to be conserved if the Hamiltonian possesses U(1) symmetry, provided any dissipation processes are linear in the system operators. As examples, we demonstrate this conservation using numerical simulations of a coupled cavity system and the Jaynes-Cummings model.

quant-ph↗
arXiv2018

Quantum optics of nonlinear systems in cascade

In this letter, we investigate the quantum optical properties of driven-dissipative nonlinear systems in a cascade configuration. We show that pumping a nonlinear system with a state having a noncoherent statistics, can improve the antibunching of the output state and, consequently, the nonclassicality of the whole system. Furthermore, we show that is possible to generate entanglement through dissipative coupling. These results applies to a broad category of physical systems with a Kerr-like non-linearity, from Rydberg atoms to exciton polaritons in microcavities.

quant-ph↗
arXiv2016

Full Stark Control of Polariton States on a Spin-Orbit Hypersphere

The orbital angular momentum and the polarisation of light are physical quantities widely investigated for classical and quantum information processing. In this work we propose to take advantage of strong light-matter coupling, circular-symmetric confinement, and transverse-electric transverse-magnetic splitting to exploit states where these two degrees of freedom are combined. To this end we develop a model based on a spin-orbit Poincaré hypersphere. Then we consider the example of semiconductor polariton systems and demonstrate full ultrafast Stark control of spin-orbit states. Moreover, by controlling states on three different spin-orbit spheres and switching from one sphere to another we demonstrate the control of different logic bits within one single physical system.

cond-mat.mes-hall↗
arXiv2016

Injection of orbital angular momentum and storage of quantized vortices in polariton superfluids

We report the experimental investigation and theoretical modeling of a rotating polariton superfluid relying on an innovative method for the injection of angular momentum. This novel, multi-pump injection method uses four coherent lasers arranged in a square, resonantly creating four polariton populations propagating inwards. The control available over the direction of propagation of the superflows allows injecting a controllable non-quantized amount of optical angular momentum. When the density at the center is low enough to neglect polariton-polariton interactions, optical singularities, associated to an interference pattern, are visible in the phase. In the superfluid regime resulting from the strong nonlinear polariton-polariton interaction, the interference pattern disappears and only vortices with the same sign are persisting in the system. Remarkably the number of vortices inside the superfluid region can be controlled by controlling the angular momentum injected by the pumps.

cond-mat.quant-gas↗
arXiv2016

Rabi oscillations of two-photon states in nonlinear optical resonators

We demonstrate that four-wave mixing processes in high-quality non-linear resonators can lead to Rabi-like oscillations in photon occupation numbers and second-order correlation functions, being a characteristic feature of the presence of entangled photon pairs in the optical signal. In the case of a system driven by a continuous coherent pump, the oscillations occur in the transient regime. We show that driving the system with pulsed coherent pumping would generate strongly anti-bunched photon states.

quant-ph↗
arXiv2015

Logic Gates with Bright Dissipative Polariton Solitons in Bragg-Cavity Systems

Optical solitons are an ideal platform for the implementation of communication lines, since they can be packed extremely close one to another without risking partial loss of the encoded information due to their interaction. On the other hand, soliton-soliton interactions are needed to implement computations and achieve all-optical information processing. Here we study how bright dissipative polariton solitons interact and exploit their interaction to implement AND and OR gates with state of the art technology. Moreover, we show that soliton-soliton interaction can be used to determine the sign of α2, the parameter describing the interaction between polaritons with opposite spin.

cond-mat.other↗