96 research outputs found
Bloch Oscillations of Einstein-Podolsky-Rosen States
Bloch Oscillations (BOs) of quantum particles manifest themselves as periodic
spreading and re-localization of the associated wave functions when traversing
lattice potentials subject to external gradient forces. Albeit BOs are deeply
rooted into the very foundations of quantum mechanics, all experimental
observations of this phenomenon so far have only contemplated dynamics of one
or two particles initially prepared in separable local states, which is well
described by classical wave physics. Evidently, a more general description of
genuinely quantum BOs will be achieved upon excitation of a Bloch-oscillator
lattice system by nonlocal states, that is, containing correlations in
contradiction with local realism. Here we report the first experimental
observation of BOs of two-particle Einstein-Podolsky-Rosen states (EPR), whose
associated N-particle wave functions are nonlocal by nature. The time evolution
of two-photon EPR states in Bloch-oscillators, whether symmetric, antisymmetric
or partially symmetric, reveals unexpected transitions from particle
antibunching to bunching. Consequently, the initial state can be tailored to
produce spatial correlations akin to bosons, fermions or anyons. These results
pave the way for a wider class of photonic quantum simulators.Comment: 21 pages, 6 figure
Generalized Schr\"odinger cat states and their classical emulation
We demonstrate that superpositions of coherent and displaced Fock states,
also referred to as generalized Schr\"odinger cats cats, can be created by
application of a nonlinear displacement operator which is a deformed version of
the Glauber displacement operator. Consequently, such generalized cat states
can be formally considered as nonlinear coherent states. We then show that
Glauber-Fock photonic lattices endowed with alternating positive and negative
coupling coefficients give rise to classical analogs of such cat states. In
addition, it is pointed out that the analytic propagator of these deformed
Glauber-Fock arrays explicitly contains the Wigner operator opening the
possibility to observe Wigner functions of the quantum harmonic oscillator in
the classical domain.Comment: 17 pages, 5 figure
Perfect transfer of path-entangled photons in J(x) photonic lattices
We demonstrate that perfect transfer of path-entangled photons as well as of single-photon states is possible in a certain class of spin inspired optical systems-the so-called J(x) photonic lattices. In these fully integrable optical arrangements, perfect cyclic transitions from correlated states to totally anticorrelated states can naturally occur. Moreover we show that the bunching and antibunching response of path-entangled photons can be preengineered at will in such coupled optical arrangements. We elucidate these effects via pertinent examples
Two-particle quantum correlations in stochastically-coupled networks
Quantum walks in dynamically-disordered networks have become an invaluable
tool for understanding the physics of open quantum systems. In this work, we
introduce a novel approach to describe the dynamics of indistinguishable
particles in noisy quantum networks. By making use of stochastic calculus, we
derive a master equation for the propagation of two non-interacting correlated
particles in tight-binding networks affected by off-diagonal dynamical
disorder. We show that the presence of noise in the couplings of a quantum
network creates a pure-dephasing-like process that destroys all coherences in
the single-particle Hilbert subspace. Remarkably, we find that when two or more
correlated particles propagate in the network, coherences accounting for
particle indistinguishability are robust against the impact of noise, thus
showing that it is possible, in principle, to find specific conditions for
which many indistinguishable particles can traverse dynamically-disordered
systems without losing their ability to interfere. These results shed light on
the role of particle indistinguishability in the preservation of quantum
coherence in dynamically-disordered quantum networks.Comment: 15 pages, 4 figure
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