Entanglement Meter: Estimation of entanglement with single copy in Interferometer

Efficient certification and quantification of high dimensional entanglement of composite systems are challenging both theoretically as well as experimentally. Here, we demonstrate that several entanglement detection methods can be implemented efficiently in a Mach-Zehnder Interferometric set-up. In particular, we demonstrate how to measure the linear entropy and the negativity of bipartite systems from the visibility of Mach-Zehnder interferometer using single copy of the input state. Our result shows that for any two qubit pure bipartite state, the interference visibility is a direct measure of entanglement. We also propose how to measure the mutual predictability experimentally from the intensity patterns of the interferometric set-up without having to resort to local measurements of mutually unbiased bases. Furthermore, we show that the entanglement witness operator can be measured in a interference setup and the phase shift is sensitive to the separable or entangled nature of the state. Our proposals bring out the power of Interferometric set-up in entanglement detection of pure and several mixed states which paves the way towards design of entanglement meter.Comment: 11 pages, 3 Figs, Comments Welcom

On quantum advantage in the random access code protocols with two-qubit states

Random access code (RAC) is an important communication task to conditionally access remote $n$-bit string even if one has limited information about it. Here we consider the version of this task assisted with shared randomness (quantum/classical) with fixed local dimension of two and the communicated information of a single classical bit. Quantum advantage is obtained in terms of worst-case success probability, $p$. We demonstrate that, there exist quantum strategies utilizing bipartite qubit state with invertible correlation matrix that outperform the corresponding dimensionally equivalent shared classical randomness source for RAC protocols when $n=2,3$. In case of $n\geq 4$ such quantum strategies do not exist for the RAC protocols considered here.Comment: 6 pages, 1 figure, improved presentatio

Anomalous behavior in temporal evolution of ripple wavelength under medium energy Ar+-ion bombardment on Si: A case of initial wavelength selection

We have studied the early stage dynamics of ripple patterns on Si surfaces, in the fluence range of 1-3 x 10(18) ions cm(-2), as induced by medium energy Ar+-ion irradiation at room temperature. Under our experimental conditions, the ripple evolution is found to be in the linear regime, while a clear decreasing trend in the ripple wavelength is observed up to a certain time (fluence). Numerical simulations of a continuum model of ion-sputtered surfaces suggest that this anomalous behavior is due to the relaxation of the surface features of the experimental pristine surface during the initial stage of pattern formation. The observation of this hitherto unobserved behavior of the ripple wavelength seems to have been enabled by the use of medium energy ions, where the ripple wavelengths are found to be order(s) of magnitude larger than those at lower ion energies.The authors are thankful to D. P. Datta from National Institute of Science Education and Research (NISER), Bhubaneswar, for his support and discussion at various stages of this work. R.C. acknowledges funding by MINECO (Spain) through Grant Nos. FIS2012-38866-C05-01 and FIS2015-66020-C2-1-P. S.K.G. acknowledges local support by Universidad Carlos III de Madrid during a short-term visit