72 research outputs found
Collision-induced squeezing in a harmonic oscillator
The concept of squeezing has so far been applied mainly to light, as is evidenced by the number of research works on the subject of squeezed light. Since, in quantum mechanics, both light and the simple harmonic oscillator are described within the same mathematical framework, there is of course no difficulty in applying the concept to the simple harmonic oscillator as well. In fact, the theoretical development of squeezed states and squeezed light owes much to the physical insights that one obtains as the analogy between light and the harmonic oscillator is exploited. The example presented shows clearly that two states with different phases in general have different degrees of squeezing, even if they have the same state distribution. This means that, even if one considers collision processes that produce the same state distribution, the degree of squeezing obtained during and after the collisions can be quite different, depending on how the phases phi(sub n) of the probability amplitudes develop in time as the collisions proceed. It is therefore evident that, for a detailed study of collision-induced squeezing, further study on the time development of the phases in collisions and its relation to collision parameters such as potential energy surfaces and collision energy is needed
Generation of Atomic Cluster States through the Cavity Input-Output Process
We propose a scheme to implement a two-qubit controlled-phase gate for single
atomic qubits, which works in principle with nearly ideal success probability
and fidelity. Our scheme is based on the cavity input-output process and the
single photon polarization measurement. We show that, even with the practical
imperfections such as atomic spontaneous emission, weak atom-cavity coupling,
violation of the Lamb-Dicke condition, cavity photon loss, and detection
inefficiency, the proposed gate is feasible for generation of a cluster state
in that it meets the scalability criterion and it operates in a conclusive
manner. We demonstrate a simple and efficient process to generate a cluster
state with our high probabilistic entangling gate
Generating arbitrary photon-number entangled states for continuous-variable quantum informatics
We propose two experimental schemes that can produce an arbitrary
photon-number entangled state (PNES) in a finite dimension. This class of
entangled states naturally includes non-Gaussian continuous-variable (CV)
states that may provide some practical advantages over the Gaussian
counterparts (two-mode squeezed states). We particularly compare the
entanglement characteristics of the Gaussian and the non-Gaussian states in
view of the degree of entanglement and the Einstein-Podolsky-Rosen correlation,
and further discuss their applications to the CV teleportation and the
nonlocality test. The experimental imperfection due to the on-off
photodetectors with nonideal efficiency is also considered in our analysis to
show the feasibility of our schemes within existing technologies.Comment: published version, 13 pages, 7 figure
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