870 research outputs found
Anisotropic quantum emitter interactions in two-dimensional photonic-crystal baths
Quantum emitters interacting with two-dimensional photonic-crystal baths
experience strong and anisotropic collective dissipation when they are
spectrally tuned to 2D Van-Hove singularities. In this work, we show how to
turn this dissipation into coherent dipole-dipole interactions with tuneable
range by breaking the lattice degeneracy at the Van-Hove point with a
superlattice geometry. Using a coupled-mode description, we show that the
origin of these interactions stems from the emergence of a qubit-photon bound
state which inherits the anisotropic properties of the original dissipation,
and whose spatial decay can be tuned via the superlattice parameters or the
detuning of the optical transition respect to the band-edges. Within that
picture, we also calculate the emitter induced dynamics in an exact manner,
bounding the parameter regimes where the dynamics lies within a Markovian
description. As an application, we develop a four-qubit entanglement protocol
exploiting the shape of the interactions. Finally, we provide a
proof-of-principle example of a photonic crystal where such interactions can be
obtained.Comment: 12 pages, 8 figure
On the spectroscopy of quantum dots in microcavities
At the occasion of the OECS conference in Madrid, we give a succinct account
of some recent predictions in the spectroscopy of a quantum dot in a
microcavity that remain to be observed experimentally, sometimes within the
reach of the current state of the art.Comment: OECS11 Conference proceedings, in editor style. 4 pages, 1 figure.
Animations provided separatel
Purely Long-Range Coherent Interactions in Two-Dimensional Structured Baths
In this work we study the quantum dynamics emerging when quantum emitters
exchange excitations with a two-dimensional bosonic bath with hexagonal
symmetry. We show that a single quantum emitter spectrally tuned to the middle
of the band relaxes following a logarithmic law in time due to the existence of
a singular point with vanishing density of states, i.e., the Dirac point.
Moreover, when several emitters are coupled to the bath at that frequency,
long-range coherent interactions between them appear which decay inversely
proportional to their distance without exponential attenuation. We analyze both
the finite and infinite system situation using both perturbative and
non-perturbative methods.Comment: 18 pages, 7 figures. Text restructured. Extended discussion on
experimental consideration
Non-Markovian Quantum Optics with Three-Dimensional State-Dependent Optical Lattices
Quantum emitters coupled to structured photonic reservoirs experience
unconventional individual and collective dynamics emerging from the interplay
between dimensionality and non-trivial photon energy dispersions. In this work,
we systematically study several paradigmatic three dimensional structured baths
with qualitative differences in their bath spectral density. We discover
non-Markovian individual and collective effects absent in simplified
descriptions, such as perfect subradiant states or long-range anisotropic
interactions. Furthermore, we show how to implement these models using only
cold atoms in state-dependent optical lattices and show how this unconventional
dynamics can be observed with these systems.Comment: 39 pages, 17 figures. Accepted versio
Multimode Fock states with large photon number: effective descriptions and applications in quantum metrology
We develop general tools to characterise and efficiently compute relevant
observables of multimode -photon states generated in non-linear decays in
one-dimensional waveguides. We then consider optical interferometry in a
Mach-Zender interferometer where a -mode photonic state enters in each arm
of the interferometer. We derive a simple expression for the Quantum Fisher
Information in terms of the average photon number in each mode, and show that
it can be saturated by number-resolved photon measurements that do not
distinguish between the different modes.Comment: 18 pages, 11 figures. V2: Minor change
Optimization of photon correlations by frequency filtering
Photon correlations are a cornerstone of Quantum Optics. Recent works [NJP 15
025019, 033036 (2013), PRA 90 052111 (2014)] have shown that by keeping track
of the frequency of the photons, rich landscapes of correlations are revealed.
Stronger correlations are usually found where the system emission is weak.
Here, we characterize both the strength and signal of such correlations,
through the introduction of the 'frequency resolved Mandel parameter'. We study
a plethora of nonlinear quantum systems, showing how one can substantially
optimize correlations by combining parameters such as pumping, filtering
windows and time delay.Comment: Small updates to take into account the recent experimental
observation of the physics here analyze
Heralded multiphoton states with coherent spin interactions in waveguide QED
WaveguideQEDoffers the possibility of generating strong coherent atomic
interactions either through appropriate atomic configurations in the
dissipative regime or in the bandgap regime. In this work, we show how to
harness these interactions in order to herald the generation of highly
entangled atomic states, which afterwards can be mapped to generate single mode
multi-photonic states with high fidelities.Weintroduce two protocols for the
preparation of the atomic states, we discuss their performance and compare them
to previous proposals. In particular, we show that one of them reaches high
probability of success for systems with many atoms but low Purcell factors
Non-reciprocal few-photon devices based on chiral waveguide-emitter couplings
We demonstrate the possibility of designing efficient, non reciprocal
few-photon devices by exploiting the chiral coupling between two waveguide
modes and a single quantum emitter. We show how this system can induce
non-reciprocal photon transport at the single-photon level and act as an
optical diode. Afterwards, we also show how the same system shows a
transistor-like behaviour for a two-photon input. The efficiency in both cases
is shown to be large for feasible experimental implementations. Our results
illustrate the potential of chiral waveguide-emitter couplings for applications
in quantum circuitry.Comment: Mathematica notebook attached for calculation of detection
probabilitie
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