Benoît Vermersch

Quantum State Transfer via Noisy Photonic and Phononic Waveguides

We describe a quantum state transfer protocol, where a quantum state of photons stored in a first cavity can be faithfully transferred to a second distant cavity via an infinite 1D waveguide, while being immune to arbitrary noise (e.g., thermal noise) injected into the waveguide. We extend the model and protocol to a cavity QED setup, where atomic ensembles, or single atoms representing quantum memory, are coupled to a cavity mode. We present a detailed study of sensitivity to imperfections, and apply a quantum error correction protocol to account for random losses (or additions) of photons in the waveguide. Our numerical analysis is enabled by matrix product state techniques to simulate the complete quantum circuit, which we generalize to include thermal input fields. Our discussion applies both to photonic and phononic quantum networks.

Magic distances in the blockade mechanism of Rydbergpanddstates

We show that the Rydberg blockade mechanism, which is well known in the case of

Quantum simulation and spectroscopy of entanglement Hamiltonians

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Non-Markovian dynamics in chiral quantum networks with spins and photons

states, can be significantly different for

Dynamical preparation of laser-excited anisotropic Rydberg crystals in 2D optical lattices

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Robust quantum state transfer via topologically protected edge channels in dipolar arrays

and

Deterministic quantum state transfer between remote qubits in cavities

d

Interacting ultracold bosons in disordered lattices: sensitivity of the dynamics to the initial state.

states due to the van der Waals couplings between different Rydberg Zeeman sublevels and the presence of a magnetic field. We show, in particular, the existence of magic distances corresponding to the laser excitation of a superposition of doubly excited states.

Emergence of nonlinear behavior in the dynamics of ultracold bosons

The properties of a strongly correlated many-body quantum system, from the presence of topological order to the onset of quantum criticality, leave a footprint in its entanglement spectrum. The entanglement spectrum is composed by the eigenvalues of the density matrix representing a subsystem of the whole original system, but its direct measurement has remained elusive due to the lack of direct experimental probes. Here we show that the entanglement spectrum of the ground state of a broad class of Hamiltonians becomes directly accessible via the quantum simulation and spectroscopy of a suitably constructed entanglement Hamiltonian, building on the Bisognano–Wichmann theorem of axiomatic quantum field theory. This theorem gives an explicit physical construction of the entanglement Hamiltonian, identified as the Hamiltonian of the many-body system of interest with spatially varying couplings. On this basis, we propose a scalable recipe for the measurement of a system’s entanglement spectrum via spectroscopy of the corresponding Bisognano–Wichmann Hamiltonian realized in synthetic quantum systems, including atoms in optical lattices and trapped ions. We illustrate and benchmark this scenario on a variety of models, spanning phenomena as diverse as conformal field theories, topological order and quantum phase transitions.The entanglement spectrum of a many-body quantum system encodes several of its properties. The construction of an artificial Hamiltonian that encodes the spectrum offers the possibility to probe it via quantum simulation or spectroscopy.

Spectral description of the dynamics of ultracold interacting bosons in disordered lattices

We study the dynamics of chiral quantum networks consisting of nodes coupled by unidirectional or asymmetric bidirectional quantum channels. In contrast to familiar photonic networks where driven two-level atoms exchange photons via 1D photonic nanostructures, we propose and study a setup where interactions between the atoms are mediated by spin excitations (magnons) in 1D