6 research outputs found
Temporally resolved second-order photon correlations of exciton-polariton Bose-Einstein condensate formation
Second-order time correlation measurements with a temporal resolution better
than 3 ps were performed on a CdTe microcavity where spontaneous Bose-Einstein
condensation is observed. After the laser pulse, the nonresonantly excited
thermal polariton population relaxes into a coherent polariton condensate.
Photon statistics of the light emitted by the microcavity evidences a clear
phase transition from the thermal state to a coherent state, which occurs
within 3.2 ps after the onset of stimulated scattering. Following this very
fast transition, we show that the emission possesses a very high coherence that
persists for more than 100 ps after the build-up of the condensate.Comment: 4 pages, 3 figure
Periodic squeezing in a polariton Josephson junction
The use of a Kerr nonlinearity to generate squeezed light is a well-known way
to surpass the quantum noise limit along a given field quadrature.
Nevertheless, in the most common regime of weak nonlinearity, a single Kerr
resonator is unable to provide the proper interrelation between the field
amplitude and squeezing required to induce a sizable deviation from Poissonian
statistics. We demonstrate experimentally that weakly coupled bosonic modes
allow exploration of the interplay between squeezing and displacement, which
can give rise to strong deviations from the Poissonian statistics. In
particular, we report on the periodic bunching in a Josephson junction formed
by two coupled exciton-polariton modes. Quantum modeling traces the bunching
back to the presence of quadrature squeezing. Our results, linking the light
statistics to squeezing, are a precursor to the study of nonclassical features
in semiconductor microcavities and other weakly nonlinear bosonic systems.Comment: 6 pages, 4 figure
Discrete step walks reveal unconventional anomalous topology in synthetic photonic lattices
Anomalous topological phases, where edge states coexist with topologically
trivial Chern bands, can only appear in periodically driven lattices. When the
driving is smooth and continuous, the bulk-edge correspondence is guaranteed by
the existence of a bulk invariant known as the winding number. However, in
lattices subject to periodic time-step walks the existence of edge states does
not only depend on bulk invariants but also on the geometry of the boundary.
This is a consequence of the absence of an intrinsic time-dependence or
micromotion in discrete-step walks. We report the observation of edge states
and a simultaneous measurement of the bulk invariants in anomalous topological
phases in a two-dimensional discrete-step walk in a synthetic photonic lattice
made of two coupled fibre rings. The presence of edge states is inherent to the
periodic driving and depends on the geometry of the boundary in the implemented
two-band model with zero Chern number. We provide a suitable expression for the
topological invariants whose calculation does not rely on micromotion dynamics.Comment: 12 pages main text plus 7 pages of apppendix (19 pages total
Anderson localisation in steady states of microcavity polaritons
We present an experimental signature of the Anderson localisation of
microcavity polaritons, and provide a systematic study of the dependence on
disorder strength. We reveal a controllable degree of localisation, as
characterised by the inverse-participation ratio, by tuning the positional
disorder of arrays of interacting mesas. This constitutes the realisation of
disorder-induced localisation in a driven-dissipative system. In addition to
being an ideal candidate for investigating localisation in this regime,
microcavity polaritons hold promise for low-power, ultra-small devices and
their localisation could be used as a resource in quantum memory and quantum
information processing.Comment: 7 pages, 3 figure
Multi-topological Floquet metals in a photonic lattice
Topological materials are usually classified according to a single topological invariant. The engineering of synthetic structures characterised by more than one class of topological invariants would open the way to the combination of different topological properties, enlarging the richness of topological phase diagrams. Using a synthetic photonic lattice implemented in a two-coupled ring system we engineer an anomalous Floquet metal that is gapless in the bulk and shows simultaneously two different topological properties. On the one hand, this synthetic lattice presents bands characterised by a winding number that directly relates to the period of Bloch oscillations within its bulk. On the other, the Floquet nature of our implementation results in well-known anomalous insulating phases with topological edge states. Our experiments open the way to study unconventional multi-topological phases in synthetic lattices