arXiv subjects

Michael Steiner

Publications and source records attributed to Michael Steiner.

24 records · Page 2Linked to original sources

arXiv2004

Study of Field-Induced Magnetic Order in Singlet-Ground-State Magnet CsFeCl$_3$

The field-induced magnetic order in the singlet-ground-state system CsFeCl$_3$ has been studied by measuring magnetization and neutron diffraction. The field dependence of intensity for the neutron magnetic reflection has clearly demonstrated that the field-induced ordered phase is described by the order parameter $ $. A condensate growth of magnons is investigated through the temperature dependence of $M_z$ and $M_{\perp}$, and this ordering is discussed in the context of a magnon Bose-Einstein condensation. Development of the coherent state and the static correlation length has been observed in the incommensurate phase in the field region of $5 < H < 6$ T at 1.8 K. At $H > H_{\rm c}$, a satellite peak was found in coexistence with the commensurate peak at the phase boundary around 10 T, which indicates that the tilt of the c-axis would be less than $\sim 0.5^{\circ}$ in the whole experiments.

cond-mat.mtrl-sci↗

arXiv2003

Genralized Robustness of Entanglement

The robustness of entanglement results of Vidal and Tarrach considered the problem whereby an entangled state is mixed with a separable state so that the overall state becomes non-entangled. In general it is known that there are also cases when entangled states are mixed with other entangled states and where the sum is separable. In this paper, we treat the more general case where entangled states can be mixed with any states so that the resulting mixture is unentangled. It is found that entangled pure states for this generalized case have the same robustness as the restricted case of Vidal and Tarrach.

quant-ph↗

arXiv2002

Entanglement in particle-detector interactions

It is predicted by Schrodinger's equation that entanglement will occur in the interaction between detector and particle. We provide an analysis of the entanglement using the Gurvitz model of double-dot and detector. New results on entangled doubled-dots are provided as well as implications on Quantum Information processing.

quant-ph↗

arXiv2000

Preserving entanglement under decoherence and sandwiching all separable states

Every entangled state can be perturbed, for instance by decoherence, and stay entangled. For a large class of pure entangled states, we show how large the perturbation can be. Our class includes all pure bipartite and all maximally entangled states. For an entangled state, E, the constucted neighborhood of entangled states is the region outside two parallel hyperplanes, which sandwich the set of all separable states. The states for which these neighborhoods are largest are the maximally entangled ones. As the number of particles, or the dimensions of the Hilbert spaces for two of the particles increases, the distance between two of the hyperplanes which sandwich the separable states goes to zero. It is easy to decide if a state Q is in the neighborhood of entangled states we construct for an entangled state E. One merely has to check if the trace of EQ is greater than a constant which depends upon E and which we determine.

quant-ph↗

arXiv2000

Entanglement of a Double Dot with a Quantum Point Contact

Entanglement between particle and detector is known to be inherent in the measurement process. Gurvitz recently analyzed the coupling of an electron in a double dot (DD) to a quantum point contact (QPC) detector. In this paper we examine the dynamics of entanglement that result between the DD and QPC. The rate of entanglement is optimized as a function of coupling when the electron is initially in one of the dots. It decreases asymptotically towards zero with increased coupling. The opposite behavior is observed when the DD is initially in a superposition: the rate of entanglement increases unboundedly as the coupling is increased. The possibility that there are conditions for which measurement occurs versus entanglement is considered.

quant-ph↗

arXiv1999

Towards Quantifying Non-Local Information Transfer: Finite-Bit Non-Locality

The advent of Bell's inequalities provoked the possibility that entangled quantum phenomena is non-local in nature. Since teleportation only requires a finite amount of classical information, i.e. two bits, the author asks whether or not it is possible to further characterize the nature of internal correlation in terms of information. Towards this end, the issue of the amount of information that is transferred internally and non-locally is addressed. There are two possibilities: the amount is infinite or the amount is finite. A partial answer to this problem is given: it is shown that models exist whereby the amount is finite. The EPR-Bell cosine correlation can be reproduced exactly using on average 1.48 bits. The issue of simultaneity and the problems it poses are also examined in this context. Several extensions are suggested.

quant-ph↗