289 research outputs found
Simulating quantum effects of cosmological expansion using a static ion trap
We propose a new experimental testbed that uses ions in the collective ground
state of a static trap for studying the analog of quantum-field effects in
cosmological spacetimes, including the Gibbons-Hawking effect for a single
detector in de Sitter spacetime, as well as the possibility of modeling
inflationary structure formation and the entanglement signature of de Sitter
spacetime. To date, proposals for using trapped ions in analog gravity
experiments have simulated the effect of gravity on the field modes by directly
manipulating the ions' motion. In contrast, by associating laboratory time with
conformal time in the simulated universe, we can encode the full effect of
curvature in the modulation of the laser used to couple the ions' vibrational
motion and electronic states. This model simplifies the experimental
requirements for modeling the analog of an expanding universe using trapped
ions and enlarges the validity of the ion-trap analogy to a wide range of
interesting cases.Comment: (v2) revisions based on referee comments, figure added for clarity;
(v1) 17 pages, no figure
Single trapped ion as a time-dependent harmonic oscillator
We show how a single trapped ion may be used to test a variety of important physical models realized as time-dependent harmonic oscillators. The ion itself functions as its own motional detector through laser-induced electronic transitions. Alsing et al., [Phys. Rev. Lett. 94, 220401 (2005)] proposed that an exponentially decaying trap frequency could be used to simulate (thermal) Gibbons-Hawking radiation in an expanding universe, but the Hamiltonian used was incorrect. We apply our general solution to this experimental proposal, correcting the result for a single ion and showing that while the actual spectrum is different from the Gibbons-Hawking case, it nevertheless shares an important experimental signature with this result
Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions
The generation of continuous-variable multipartite entangled states is
important for several protocols of quantum information processing and
communication, such as one-way quantum computation or controlled dense coding.
In this article we theoretically show that multimode optical parametric
oscillators can produce a great variety of such states by an appropriate
control of the parametric interaction, what we accomplish by tailoring either
the spatio-temporal shape of the pump, or the geometry of the nonlinear medium.
Specific examples involving currently available optical parametric oscillators
are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure
Towards universal quantum computation through relativistic motion
We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tuneable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes
Theory of quantum frequency translation of light in optical fiber: application to interference of two photons of different color
We study quantum frequency translation and two-color photon interference
enabled by the Bragg scattering four-wave mixing process in optical fiber.
Using realistic model parameters, we computationally and analytically determine
the Green function and Schmidt modes for cases with various pump-pulse lengths.
These cases can be categorized as either "non-discriminatory" or
"discriminatory" in regards to their propensity to exhibit high-efficiency
translation or high-visibility two-photon interference for many different
shapes of input wave packets or for only a few input wave packets,
respectively. Also, for a particular case, the Schmidt mode set was found to be
nearly equal to a Hermite-Gaussian function set. The methods and results also
apply with little modification to frequency conversion by sum-frequency
conversion in optical crystals
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