3,300 research outputs found
Single Photon Subradiance: Quantum control of spontaneous emission and ultrafast readout
Recent work has shown that collective single photon emission from an ensemble
of resonate two-level atoms, i.e. single photon superradiance, is a rich field
of study. The present paper addresses the flip side of superradiance, i.e.
subradiance. Single photon subradiant states are potentially stable against
collective spontaneous emission and can have ultrafast readout. In particular
it is shown how many atom collective effects provide a new way to control
spontaneous emission by preparing and switching between subradiant and
superradiant states.Comment: 17 pages, 6 figures, and 1 tabl
From EIT photon correlations to Raman anti-correlations in coherently prepared Rb vapor
We have experimentally observed switching between photon-photon correlations
(bunching) and anti-correlations (anti-bunching) between two orthogonally
polarized laser beams in an EIT configuration in Rb vapor. The bunching and
anti-bunching sswitching occurs at a specific magnetic field strength.Comment: 4 pages and 3 figure
On mechanisms that enforce complementarity
In a recent publication Luis and Sanchez-Soto arrive at the conclusion that
complementarity is universally enforced by random classical phase kicks. We
disagree. One could just as well argue that quantum entanglement is the
universal mechanism. Both claims of universality are unjustified, however.Comment: 4 page
Cooling a quantum circuit via coupling to a multiqubit system
The cooling effects of a quantum LC circuit coupled inductively with an
ensemble of artificial qubits are investigated. The particles may decay
independently or collectively through their interaction with the environmental
vacuum electromagnetic field reservoir. For appropriate bath temperatures and
the resonator's quality factors, we demonstrate an effective cooling well below
the thermal background. In particular, we found that for larger samples the
cooling efficiency is better for independent qubits. However, the cooling
process can be faster for collectively interacting particles.Comment: 5 pages, 3 figure
Heisenberg Limit Superradiant Superresolving Metrology
We propose a superradiant metrology technique to achieve the Heisenberg limit
super-resolving displacement measurement by encoding multiple light momenta
into a three-level atomic ensemble. We use coherent pulses to prepare a
single excitation superradiant state in a superposition of two timed Dicke
states that are light momenta apart in momentum space. The phase
difference between these two states induced by a uniform displacement of the
atomic ensemble has sensitivity. Experiments are proposed in crystals
and in ultracold atoms
Fluorescence interferometry
We describe an interferometer based on fluorescent emission of radiation of
two qubits in quasi-one-dimensional modes. Such a system can be readily
realized with dipole emitters near conducting surface-plasmonic nanowires or
with superconducting qubits coupled to coplanar waveguide transmission lines.Comment: 7 pages, 2 figure
Preventing Multipartite Disentanglement by Local Modulations
An entangled multipartite system coupled to a zero-temperature bath undergoes
rapid disentanglement in many realistic scenarios, due to local,
symmetry-breaking, differences in the particle-bath couplings. We show that
locally controlled perturbations, addressing each particle individually, can
impose a symmetry, and thus allow the existence of decoherence-free
multipartite entangled systems in zero-temperature environments.Comment: 5 pages, 2 figure
Generation of two-mode field squeezing through selective dynamics in cavity QED
We propose a scheme for the generation of a two-mode field squeezed state in
cavity QED. It is based on two-channel Raman excitations of a beam of
three-level atoms with random arrival times by two classical fields and two
high-Q resonator modes. It is shown that by suitably choosing the intensities
and detunings of fields the dynamical processes can be selective and two-mode
squeezing between the cavity modes can be generated at steady state. This
proposal does not need the preparation of the initial states of atoms and
cavity modes, and is robust against atomic spontaneous decay.Comment: 4 pages,2 figure
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