Determination of When an Outcome is Actualised in a Quantum Measurement using DNA - Photolyase System

The biochemical attachment of photolyase to ultraviolet (uv) absorbed DNA molecules provides a method for registering whether a source has emitted photons. Here using laws of chemical kinetics and related experimental methods we argue that the instant after which this information becomes discernible can be empirically determined by retrodicting from relevant data when the photolyase binding to uv-absorbed DNA molecules has started occuring. Thus an empirically investigable twist is provided to the quantum measurement problem.Comment: 9 Pages,LaTeX,Revised Communicating author: Rajagopal Chattopadhyay, [email protected]

Barrier Perturbation Induced Superarrivals and Nonlocality in a Time-Evolving Wave Packet

We compute the time evolving probability of a Gaussian wave packet to be reflected from a rectangular potential barrier which is perturbed by reducing its height. A time interval is found during which this probability of reflection is enhanced (superarrivals) compared to the unperturbed case. Such a time evolving reflection probability implies that the effect of perturbation propagates across the wave packet faster than its group velocity - a curious form of nonlocality.Comment: latex, 6 figure

Bell's Inequality, Quantum Measurement and Einstein Realism: A Unified Perspective

The logical foundations of Bell's inequality are reexamined. We argue that the form of the reality condition that underpins Bell's inequality comes from the requirement of solving the quantum measurement problem. Hence any violation of Bell's inequality necessarily implies nonlocality because of the measurement problem. The differences in the implications of deterministic and stochastic formulations of Bell's inequality are highlighted. The reality condition used in Bell's inequality is shown to be a generalisation of Einstein's later form of realism.Comment: 15 page

Interpreting the time of decay measurement: phenomenological significance of the Bohm model

We point out that the spreading of wave packets could be significant in affecting the analysis of experiments involving the measurement of time of decay. In particular, we discuss a hitherto unexplored application of the Bohm model in properly taking into account the nontrivial effect of wave packet spreading in the CP violation experiment.Comment: 8 pages, Late

Ipso-information-transfer

A tripartite system with entangled non-orthogonal states is used to transfer retrievable or usable information without requiring an external channel, ipso-information-transfer (IIT). The non-Schmidt decomposable entanglement couples two independent interactions through which the information is transferred between a pair of non-interacting components of the system. We outline a dynamical model of IIT using localised particles. Implications for quantum nonlocality are raised.Comment: 4 pages, no figure

On the possibility of empirically probing the Bohmian model in terms of the testability of quantum arrival/transit time distribution

The present article focuses on studying the extent to which the nonuniqueness that is inherent in the standard quantum mechanical calculation of arrival/transit time distribution can be exploited to enable an empirical scrutiny of any causal trajectory model such as the Bohmian scheme. For this purpose, we consider the example of spin-1/2 neutral particles corresponding to a wave packet which passes through a spin rotator(SR) that contains constant magnetic field confined within a region - in such a case, the transit time distribution can be measured in terms of the spin distribution of particles emerging from the SR. In particular, we investigate the way one can compare the Bohmian predictions obtained for this example with that using one of the quantum approaches, say, the probability current density based scheme. Here the Bohmian calculational procedure involves a couple of critical subtleties that lead to some specific directions for further studies.Comment: 18 pages, 1 Figur

Testing local-realism and macro-realism under generalized dichotomic measurements

Generalised quantum measurements with two outcomes are fully characterised by two real parameters, dubbed as sharpness parameter and biasedness parameter and they can be linked with different aspects of the experimental setup. It is known that precision of measurements, characterised by the sharpness parameter of the measurements, reduces the possibility of probing quantum features like violation of local-realism (LR) or macro-realism (MR). Here we investigate the effect of biasedness together with sharpness of measurement and find a trade-off between those two parameters in the context of probing violation of LR and MR. Interestingly we also find the above mentioned trade-off is more robust in the later case.Comment: 10 pages, 3 figure

Manifestation of pointer state correlations in complex weak values of quantum observables

In the weak measurement (WM) scenario involving weak interaction and postselection by projective measurement, the empirical significance of weak values is manifested in terms of shifts in the measurement pointer's mean position and mean momentum. In this context, a general quantitative treatment is presented in this paper by taking into account the hitherto unexplored effect of correlations among the pointer degrees of freedom which pertain to an arbitrary multidimensional preselected pointer state. This leads to an extension of the earlier results, showing that, for complex weak values, the correlations among different pointer degrees of freedom can crucially affect the way the imaginary parts of the weak values are related to the observed shifts of the mean pointer position and momentum. The particular relevance of this analysis is discussed in the case of sequential weak interactions, followed by a postselection (called sequential WM) which, in the special case, reduces to the usual WM scheme involving a single weak interaction and postseletion, modified by the effect of pointer state correlations

A testable prediction of the no-signalling condition using a variant of the EPR-Bohm example

Predictive power of the no-signalling condition (NSC) is demonstrated in a testable situation involving a non-ideal Stern-Gerlach (SG) device in one of the two wings of the EPR-Bohm entangled pairs. In this wing, for two types of measurement in the other wing, we consider the spin state of a selected set of particles that are confined to a particular half of the plane while emerging from the SG magnetic field region. Due to non-idealness of the SG setup, this spin state will have superposing components involving a relative phase for which a testable quantitative constraint is obtained by invoking NSC, thereby providing a means for precision testing of this fundamentally significant principle.Comment: 7 page

Communicating with a wave packet using quantum superarrival

An analytical treatment of a propagating wave packet incident on a transient barrier reveals a counterintuitive quantum mechanical effect in which, for a particular time interval, the time-varying transmission probability {\it exceeds} (`superarrival') that for the free propagation of the wave packet. It is found that the speed with which the information about the barrier perturbation propagates across the wave packet can exceed the group velocity of the wave packet. An interesting implication of this effect regarding information transfer is analyzed by showing one-to-one correspondence between the strength of the barrier and the magnitude of `superarrival'.Comment: 4 pages, latex, 3 fig