arXiv subjects

Ran Ber

Publications and source records attributed to Ran Ber.

5 recordsLinked to original sources

arXiv2016

Weak value beyond conditional expectation value of the pointer readings

It is argued that a weak value of an observable is a robust property of a single pre- and post-selected quantum system rather than a statistical property. During an infinitesimal time a system with a given weak value affects other systems as if it were in an eigenstate with eigenvalue equal to the weak value. This differs significantly from the action of a system pre-selected only and possessing a numerically equal expectation value. The weak value has a physical meaning beyond a conditional average of a pointer in the weak measurement procedure. The difference between the weak value and the expectation value has been demonstrated on the example of photon polarization. In addition, the weak values for systems pre- and post-selected in mixed states are considered.

quant-ph↗

arXiv2016

Remote State Preparation for Quantum Fields

Remote state preparation is generation of a desired state by a remote observer. In spite of causality, it is well known, according to the Reeh-Schlieder theorem, that it is possible for relativistic quantum field theories, and a "physical" process achieving this task, involving superoscillatory functions, has recently been introduced. In this work we deal with non-relativistic fields, and show that remote state preparation is also possible for them, hence obtaining a Reeh-Schlieder-like result for general fields. Interestingly, in the nonrelativistic case, the process may rely on completely different resources than the ones used in the relativistic case.

quant-ph↗

arXiv2015

Superoscillations underlying remote state preparation for relativistic fields

We present a physical (gedanken) implementation of a generalized remote state preparation of relativistic quantum field states for an arbitrary set of observers. The prepared states are created in regions that are outside the future light-cone of the generating region. The mechanism, which is based on utilizing the vacuum state of a relativistic quantum field as a resource, sheds light on the well known Reeh-Schlieder theorem, indicating its strong connection with the mathematical phenomenon of superoscillations.

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arXiv2015

Unusual Transitions Made Possible by Superoscillations

We present a physical scenario in which an electromagnetic field in a state consisted of photons whose energies are smaller than the energy gap of a two-state particle, interacts with the particle, for an arbitrarily long duration, as if it was consisted of photons whose energy matches the energy gap of the particle. This type of interaction is possible when the field is in a specially tailored state whose magnetic field's expectation value is a superoscillatory function.

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arXiv2013

Process Tomography for Systems in a Thermal State

We propose a new method for implementing process tomography that is based on the information extracted from temporal correlations between observables, rather than on state preparation and state tomography. As such, the approach is applicable to systems that are in a mixed state, and in particular to thermal states. We illustrate the method for an arbitrary evolution described by Kraus operators, as well as for simpler cases such as a general Gaussian channels, and qubit dynamics.

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