arXiv subjects

Ran Wei

Publications and source records attributed to Ran Wei.

75 records · Page 5Linked to original sources

arXiv2011

Deterministic spin-wave interferometer based on Rydberg blockade

The spin-wave (SW) NOON state is an $N$-particle Fock state with two atomic spin-wave modes maximally entangled. Attributed to the property that the phase is sensitive to collective atomic motion, the SW NOON state can be utilized as a novel atomic interferometer and has promising application in quantum enhanced measurement. In this paper we propose an efficient protocol to deterministically produce the atomic SW NOON state by employing Rydberg blockade. Possible errors in practical manipulations are analyzed. A feasible experimental scheme is suggested. Our scheme is far more efficient than the recent experimentally demonstrated one, which only creates a heralded second-order SW NOON state.

quant-ph↗

arXiv2010

Light pulse in $Λ$-type cold atomic gases

We investigate the behavior of the light pulse in $Lambda$-type cold atomic gases with two counterpropagating control lights with equal strength by directly simulating the dynamic equations and exploring the dispersion relation. Our analysis shows that, depending on the length $L_0$ of the stored wave packet and the decay rate $γ$ of ground-spin coherence, the recreated light can behave differently. For long $L_0$ and/or large $γ$, a stationary light pulse is produced, while two propagating light pulses appear for short $L_0$ and/or small $γ$. In the $γ\to 0$ limit, the light always splits into two propagating pulses for sufficiently long time. This scenario agrees with a recent experiment [Y.-W.Lin, et al., Phys. Rev. Lett. 102, 213601(2009)] where two propagating light pulses are generated in laser-cooled cold atomic ensembles.

quant-ph↗

arXiv2009

Interaction between two non-threshold bound states

A general non-threshold BPS (F, D$_p$) (or (D$_{p - 2}$, D$_p$)) bound state can be described by a boundary state with a quantized world-volume electric (or magnetic) flux and is characterized by a pair of integers $(m, n)$. With this, we calculate explicitly the interaction amplitude between two such non-threshold bound states with a separation $Y$ when each of the states is characterized by a pair of integers ($m_i, n_i$) with $i = 1, 2$. With this result, one can show that the non-degenerate (i.e., $m_i n_i \neq 0$) interaction is in general attractive for the case of (D$_{p - 2}$, D$_p$) but this is true and for certain only at large separation for the case of (F, D$_p$). In either case, this interaction vanishes only if $m_1/ n_1 = m_2/ n_2$ and $n_1 n_2 > 0$. We also study the analytic structure of the corresponding amplitude and calculate in particular the rate of pair production of open strings in the case of (F, D$_p$).

hep-th↗