5,048 research outputs found
Adiabatic State Conversion and Pulse Transmission in Optomechanical Systems
Full text linkOptomechanical systems with strong coupling can be a powerful medium for
quantum state engineering. Here, we show that quantum state conversion between
cavity modes with different wavelengths can be realized with high fidelity by
adiabatically varying the effective optomechanical couplings. The fidelity for
the conversion of gaussian states is derived by solving the Langevin equation
in the adiabatic limit. We also show that photon pulses can be transmitted
between input-output channels with different wavelengths via the effective
optomechanical couplings and the output pulse shape can also be manipulated.Comment: 5 pages, 2 figures. Supplementary Materials at
http://prl.aps.org/supplemental/PRL/v108/i15/e15360
Distributing fully optomechanical quantum correlations
Full text linkWe present a scheme to prepare quantum correlated states of two mechanical
systems based on the pouring of pre-available all-optical entanglement into the
state of two micro-mirrors belonging to remote and non-interacting
optomechanical cavities. We show that, under realistic experimental conditions,
the protocol allows for the preparation of a genuine quantum state of a
composite mesoscopic system whose non-classical features extend far beyond the
occurrence of entanglement. We finally discuss a way to access such mechanical
correlations.Comment: 5 pages, 4 figures, to appear in Physical Review
Entanglement detection by Bragg scattering
Full text linkWe show how to measure the structural witnesses proposed in [P. Krammer et
al., Phys. Rev. Lett. 103, 100502 (2009)] for detecting entanglement in a spin
chain using photon scattering. The procedure, moreover, allows one to measure
the two-point correlation function of the spin array. This proposal could be
performed in existing experimental platforms realizing ion chains in Paul traps
or atomic arrays in optical lattices.Comment: 4 pages, 2 figures, final version (refs added + minor changes
Optical wavelength conversion of quantum states with optomechanics
Full text linkAn optomechanical interface that converts quantum states between optical
fields with distinct wavelengths is proposed. A mechanical mode couples to two
optical modes via radiation pressure and mediates the quantum state mapping
between the two optical modes. A sequence of optomechanical pulses
enables state-swapping between optical and mechanical states as well as the
cooling of the mechanical mode. Theoretical analysis shows that high fidelity
conversion can be realized for states with small photon numbers in systems with
experimentally achievable parameters. The pulsed conversion process also makes
it possible to maintain high conversion fidelity at elevated bath temperatures.Comment: 4 pages, 4 figures, Fig. 4 looks weird (possible latex style problem
Long-lived selective spin echoes in dipolar solids under periodic and aperiodic pi-pulse trains
Full text linkThe application of Carr-Purcell-Meiboom-Gill (CPMG) trains for
dynamically decoupling a system from its environment has been extensively
studied in a variety of physical systems. When applied to dipolar solids,
recent experiments have demonstrated that CPMG pulse trains can generate
long-lived spin echoes. While there still remains some controversy as to the
origins of these long-lived spin echoes under the CPMG sequence, there is a
general agreement that pulse errors during the pulses are a necessary
requirement. In this work, we develop a theory to describe the spin dynamics in
dipolar coupled spin-1/2 system under a CPMG() pulse train,
where and are the phases of the pulses. From our
theoretical framework, the propagator for the CPMG() pulse
train is equivalent to an effective ``pulsed'' spin-locking of single-quantum
coherences with phase , which generates a
periodic quasiequilibrium that corresponds to the long-lived echoes. Numerical
simulations, along with experiments on both magnetically dilute, random spin
networks found in C and C and in non-dilute spin systems found in
adamantane and ferrocene, were performed and confirm the predictions from the
proposed theory.Comment: 25 pages, 12 figures, submitted to Physical Review
General linewidth formula for steady-state multimode lasing in arbitrary cavities
Full text linkA formula for the laser linewidth of arbitrary cavities in the multimode
non-linear regime is derived from a scattering analysis of the solutions to
semiclassical laser theory. The theory generalizes previous treatments of the
effects of gain and openness described by the Petermann factor. The linewidth
is expressed using quantities based on the non-linear scattering matrix, which
can be computed from steady-state ab initio laser theory; unlike previous
treatments, no passive cavity or phenomenological parameters are involved. We
find that low cavity quality factor, combined with significant dielectric
dispersion, can cause substantial deviations from the Schawlow-Townes-Petermann
theory.Comment: 5 pages, 2 figure
The Electromagnetically Induced Transparency in Mechanical Effects of Light
Get PDFWe consider the dynamical behavior of a nanomechanical mirror in a
high-quality cavity under the action of a coupling laser and a probe laser. We
demonstrate the existence of the analog of electromagnetically induced
transparency (EIT) in the output field at the probe frequency. Our calculations
show explicitly the origin of EIT-like dips as well as the characteristic
changes in dispersion from anomalous to normal in the range where EIT dips
occur. Remarkably the pump-probe response for the opto mechanical system shares
all the features of the Lambda system as discovered by Harris and
collaborators.Comment: 4 pages, 5 figure
Implementation of controlled SWAP gates for quantum fingerprinting and photonic quantum computation
Get PDFWe propose a scheme to implement quantum controlled SWAP gates by directing
single-photon pulses to a two-sided cavity with a single trapped atom. The
resultant gates can be used to realize quantum fingerprinting and universal
photonic quantum computation. The performance of the scheme is characterized
under realistic experimental noise with the requirements well within the reach
of the current technology.Comment: 4 page
Quantum decoherence reduction by increasing the thermal bath temperature
Full text linkThe well-known increase of the decoherence rate with the temperature, for a
quantum system coupled to a linear thermal bath, holds no longer for a
different bath dynamics. This is shown by means of a simple classical
non-linear bath, as well as a quantum spin-boson model. The anomalous effect is
due to the temperature dependence of the bath spectral profile. The decoherence
reduction via the temperature increase can be relevant for the design of
quantum computers
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