Coherent manipulation of spin-wave vector for polarization of photons in an atomic ensemble

Abstract

We experimentally demonstrate the manipulation of two-orthogonal components of a spin wave in an atomic ensemble. Based on Raman two-photon transition and Larmor spin precession induced by magnetic field pulses, the coherent rotations between the two components of the spin wave is controllably achieved.Successively, the two manipulated spin-wave components are mapped into two orthogonal polarized optical emissions, respectively. By measuring Ramsey fringes of the retrieved optical signals, the π/2-pulse fidelity of ~96% is obtained. The presented manipulation scheme can be used to build an arbitrary rotation for qubit operations in quantum information processing based on atomic ensembles.

The effect of impurity and the suppression of superconductivity in Na(Fe0.97−xCo0.03Tx)As (T = Cu, Mn)

“…In efforts to resolve the mystery of the superconducting mechanism, plenty of experiments have been carried out on the impurity effects in iron-based superconductors. Ways to introduce scattering centers include chemical substitutions [21][22][23][24][25][26][27][28][29][30][31][32][33] and particle irradiations [34][35][36][37][38]. Unfortunately, the conclusions remain highly controversial.…”

“…Previous studies on Mn impurities showed that T c was strongly suppressed in Ba 0.5 K 0.5 Fe 2 As 2 [21,23] and Ba(Fe −y 1 Co y ) 2 As 2 systems [24], while T c is not suppressed or is even enhanced in Mn-doped FeSe 0.5 Te 0.5 superconductors [26]. Zn impurity suppresses T c rapidly in BaFe − x 1.89 2 Zn x 2 Co 0.11 As 2 [25], whereas the superconducting state is retained robustly in Fe −y 1 Zn y Se 0.3 Te 0.7 [27]. Theoretically it is proposed that the pairing symmetry in iron-based superconductors can differ from material to material [7].…”

Quantum storage of optical signals and coherent manipulation of quantum states based on electromagnetically induced transparency

“…The measured optical depth of the cold atoms is about 1.5 and the trap temperature can reach ~200 µK (see [12] for the experimental details).…”

“…In 2011, we demonstrated an experiment on the two unitary rotations R(,) and R z ( z ) on the basis of their formation by two orthogonal spin waves in an atomic ensemble [12]. The relevant 87 Rb levels involved in the storage, Raman manipulation and readout processes are shown in Figure 11 …”

“…In this paper, we briefly review the experimental studies of enhanced cross-phase modulation based on double EIT [10], the quantum interference of stored dual-channel spinwave excitations [11], and the coherent manipulation of the spin wave vector for the polarization of photons [12] in a four-level tripod atomic system, which were conducted by our group over the last few years.…”