arXiv subjects

Fatemeh Rezazadeh

Publications and source records attributed to Fatemeh Rezazadeh.

3 recordsLinked to original sources

arXiv2024

Witnessing entanglement of remote particles with incomplete teleportation

Having common reference frames or aligned coordinate systems, is one of the presumptions in witnessing entanglement in a two-party state possessed by two remote parties. This assumption may fail for many reasons. With an unlimited supply of singlet states, the two parties can first align their coordinate systems and then measure any entanglement witness. In this article, we propose an alternative method which uses the same resource for incomplete teleportation of states between the two parties, enabeling them to witness the entanglement of any shared state by local measurements without the need of prior alignment of the coordinate systems. The method works for any kind of witness and in any dimension. Beyond the context of Entanglement Witnesses, our method works also for remote measurements of observables of particles (entangled or not) in laboratories which may have deficiency in their resources.

quant-ph↗

arXiv2024

Quantum coherence between subspaces: State transformation, Cohering Power, $k$-coherence and other properties

The concept of bock-coherence, first introduced in [1] and developed in [2,3] encompasses the case where experimental capabilities are not so delicate to perform arbitrary refined measurements on individual atoms. We develop a framework which facilitates further investigation of this resource theory in several respects. Using this framework, we investigate the problem of state conversion by incoherent operations and show that a majorization condition is the necessary and sufficient condition for state transformation by block-incoherent operations. We also determine the form of the maximally coherent state from which all other states and all unitary gates can be constructed by incoherent operations. Thereafter, we define the concept of block-cohering and block-decohering powers of quantum channels and determine these powers for several types of channels. Finally, we explore the relation between block coherence and a previous extension of coherence, known as $k$-coherence.

quant-ph↗

arXiv2019

Quantum Key Distribution with no Shared Reference Frame

Any quantum communication task requires a common reference frame (i.e. phase, coordinate system). In particular, Quantum Key Distribution requires different bases for preparation and measurements of states which are obviously based on the existence of a common frame of reference. Here we show how QKD can be achieved in the absence of any common frame of reference. We study the coordinate reference frame, where the two parties do not even share a single direction, but the method can be generalized to other general frames of reference, pertaining to other groups of transformations.

quant-ph↗