11,242 research outputs found
Entanglement between an electron and a nuclear spin 1/2
We report on the preparation and detection of entangled states between an
electron spin 1/2 and a nuclear spin 1/2 in a molecular single crystal. These
were created by applying pulses at ESR (9.5 GHz) and NMR (28 MHz) frequencies.
Entanglement was detected by using a special entanglement detector sequence
based on a unitary back transformation including phase rotation.Comment: 4 pages, 3 figure
Complex Velocity Fields in the Shell of T Pyxidis
We present spatially-resolved, moderate-resolution spectrophotometry of the
recurrent nova T Pyx and a portion of the surrounding shell. The spectrum
extracted from a strip of width 10'' centered on the star shows well-known,
strong emission lines typical of old novae, plus a prominent, unfamiliar
emission line at 6590 Angstroms. This line, and a weaker companion at 6540
Angstroms which we also detect, have been previously reported by Shahbaz et
al., and attributed to Doppler-shifted H alpha emission from a collimated jet
emerging from T Pyx. We demonstrate that these lines are instead due to [NII]
6548, 6584 from a complex velocity field in the surrounding nebula. The
comments of past workers concerning the great strength of HeII 4686 in T Pyx
itself are also reiterated.Comment: 8 pages including 2 figures; Accepted for publication in The
Astrophysical Journal Letter
Quantum spatial propagation of squeezed light in a degenerate parametric amplifier
Differential equations which describe the steady state spatial evolution of nonclassical light are established using standard quantum field theoretic techniques. A Schroedinger equation for the state vector of the optical field is derived using the quantum analog of the slowly varying envelope approximation (SVEA). The steady state solutions are those that satisfy the time independent Schroedinger equation. The resulting eigenvalue problem then leads to the spatial propagation equations. For the degenerate parametric amplifier this method shows that the squeezing parameter obey nonlinear differential equations coupled by the amplifier gain and phase mismatch. The solution to these differential equations is equivalent to one obtained from the classical three wave mixing steady state solution to the parametric amplifier with a nondepleted pump
The path-coalescence transition and its applications
We analyse the motion of a system of particles subjected a random force
fluctuating in both space and time, and experiencing viscous damping. When the
damping exceeds a certain threshold, the system undergoes a phase transition:
the particle trajectories coalesce. We analyse this transition by mapping it to
a Kramers problem which we solve exactly. In the limit of weak random force we
characterise the dynamics by computing the rate at which caustics are crossed,
and the statistics of the particle density in the coalescing phase. Last but
not least we describe possible realisations of the effect, ranging from
trajectories of raindrops on glass surfaces to animal migration patterns.Comment: 4 pages, 3 figures; revised version, as publishe
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