Advantage Of Quantum Coherence Research Articles

Can NSI affect non-local correlations in neutrino oscillations?

Non-local correlations in entangled systems are usually captured by measures such as Bell’s inequality violation. It was recently shown that in neutrino systems, a measure of non-local advantage of quantum coherence (NAQC) can be considered as a stronger measure of non-local correlations as compared to the Bell’s inequality violation. In this work, we analyze the effects of non standard interaction (NSI) on these measures in the context of two flavour neutrino oscillations for DUNE, MINOS, T2K, KamLAND, JUNO and Daya Bay experimental set-ups. We find that even in the presence of NSI, Bell’s inequality violation occurs in the entire energy range whereas the NAQC violation is observed only in some specific energy range justifying the more elementary feature of NAQC. Further, we find that NSI can enhance the violation of NAQC and Bell’s inequality parameter in the higher energy range of a given experimental set-up; these enhancements being maximal for the KamLAND experiment. However, the possible enhancement in the violation of the Bell’s inequality parameter over the standard model prediction can be up to 11% whereas for NAQC it is 7%. Thus although NAQC is a comparatively stronger witness of nonclassicality, it shows lesser sensitivity to NSI effects in comparison to the Bell’s inequality parameter.

Nonlocal advantage of quantum coherence under relativistic frame

In this paper, we investigate the influence of the Unruh effect on the achievement of the nonlocal advantage of quantum coherence for a two-qubit system under a relativistic frame. The results show that with the increase of acceleration, it is difficult to realize the nonlocal advantage of quantum coherence and when the acceleration exceeds a certain value, nonlocal advantage of quantum coherence cannot be realized. In addition, we explore the dynamics of Bell nonlocality, steering, quantum coherence, entanglement and quantum discord (QD) under Unruh thermal noise. It is shown that nonlocal advantage of quantum coherence, Bell nonlocality, steering and entanglement experience “sudden death” for a finite acceleration, while quantum coherence and QD vanish only in the limit of an infinite acceleration. We also find that not all nonlocal states can achieve the nonlocal advantage of quantum coherence. It is also demonstrated that the robustness of Bell nonlocality is better than nonlocal advantage of quantum coherence under the influence of the Unruh noise.

Charm Mixing and D Dalitz Analysis at BESIII

We study D0D‾0 pairs produced in e+e− collisions at s=3.773GeV using a data sample of 2.92fb−1 collected with the BESIII detector. Using world-average values of external parameters, we obtain cosδKπ=1.02±0.11±0.06±0.01, δKπ is the strong phase difference between the doubly Cabibbo-suppressed process D‾0→K−π+ and the Cabibbo-favored process D0→K−π+. A measurement of the parameter yCP in D0−D‾0 oscillations is performed by taking advantage of quantum coherence between pair-produced D0 and D‾0 mesons near threshold, the preliminary result is yCP=(−1.6±1.3±0.6)%. An analysis of the D+→KS0π+π0 Dalitz plot is performed, the Dalitz plot is found to be well presented by a combination of six quasi-two-body decay channels [KS0ρ+, KS0ρ(1450)+, K‾⁎0π+, K‾0(1430)0π+, K‾(1680)0π+, κ‾0π+] plus a small nonresonant component. Using the fit fractions from this analysis, partial branching ratios are updated with higher precision than previous measurements.

Measurement of [formula omitted] in [formula omitted] oscillation using quantum correlations in [formula omitted] at [formula omitted

We report a measurement of the parameter yCP in D0–D¯0 oscillations performed by taking advantage of quantum coherence between pairs of D0D¯0 mesons produced in e+e− annihilations near threshold. In this work, doubly-tagged D0D¯0 events, where one D decays to a CP eigenstate and the other D decays in a semileptonic mode, are reconstructed using a data sample of 2.92 fb−1 collected with the BESIII detector at the center-of-mass energy of s=3.773 GeV. We obtain yCP=(−2.0±1.3±0.7)%, where the first uncertainty is statistical and the second is systematic. This result is compatible with the current world average.

Theoretical examination of quantum coherence in a photosynthetic system at physiological temperature

The observation of long-lived electronic coherence in a photosynthetic pigment-protein complex, the Fenna-Matthews-Olson (FMO) complex, is suggestive that quantum coherence might play a significant role in achieving the remarkable efficiency of photosynthetic electronic energy transfer (EET), although the data were acquired at cryogenic temperature [Engel GS, et al. (2007) Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. Nature 446:782-786]. In this paper, the spatial and temporal dynamics of EET through the FMO complex at physiological temperature are investigated theoretically. The numerical results reveal that quantum wave-like motion persists for several hundred femtoseconds even at physiological temperature, and suggest that the FMO complex may work as a rectifier for unidirectional energy flow from the peripheral light-harvesting antenna to the reaction center complex by taking advantage of quantum coherence and the energy landscape of pigments tuned by the protein scaffold. A potential role of quantum coherence is to overcome local energetic traps and aid efficient trapping of electronic energy by the pigments facing the reaction center complex.

Quantum search protocol for an atomic array

Quantum computers can, in principle, exceed the speed of ordinary computers by taking advantage of quantum coherence and entanglement. It is possible to find a ``needle in a haystack'' of $N\ensuremath{-}1$ straws in only $\sqrt{N}$ searches by utilizing coherent superposition states. In the present paper we show how modern quantum optics may provide a simple and practicable quantum search procedure, which may also yield insights into quantum search algorithms in general.