"The second quantum revolution and birth of quantum
information science owes its existence to the superposition of quantum
states. Some dramatic recent results hint at a possible further
revolution in quantum technology, this time harnessing the
superposition of quantum processes. In this talk, I shall discuss some
of the peculiar effects that happen when such superpositions are
created. They span the gamut of usual quantum technologies - from
increasing classical capacity of quantum channels to perfect
teleportation in noisy channels to improved thermometry to universal
"Quantum information theory is a relatively new field which lies
at the intersection of the two important sciences of the twentieth century:
the quantum theory and information theory. The two fundamental questions
which drives research in this area are: What are the ultimate capabilities
of computation and information processing with quantum mechanical systems?
In the last two decades investigations into this question have blossomed
into a rich area of research. In this talk, we will discuss a new framework
and tools for designing communication protocols over quantum channels. This
framework also gives a unified approach for designing optimal classical
protocols for many network communication scenarios."
TCS Seminar | Alladi Ramakrishnan Hall
Jan 18 15:30-16:30
C. Jebarathinam, S. N. Bose National Centre for Basic Sciences
"In recent years, exploration of the possible use of separable states as a resource to achieve quantum information processing (QIP) tasks has been gaining increasing significance. In this context, a particularly important demonstration has been that nonvanishing discord is the necessary condition for separable states to be used as a resource for remotely preparing any arbitrary pure target state [Nat. Phys. 8, 666 (2012)]. The present work stems from our observation that not only can resource states with the same discord imply different efficiencies (in terms of average fidelity) of the remote state preparation (RSP) protocol, but also states with higher discord can imply lower RSP efficiency. Therefore, this necessitates identification of the relevant feature of quantum correlations that can appropriately quantify the effectiveness of the resource state for the RSP protocol. To this end, for the two-qubit Bell-diagonal states, we show that an appropriate measure of simultaneous correlations in three mutually unbiased bases can serve to quantify the usefulness of the resource for the RSP task using entangled as well as separable states, including nondiscordant states as a resource. In particular, it is revealed that zero-discord states with such a nonvanishing measure can be useful for remotely preparing a subset of pure target states. Thus, this work shows that, using separable states, an effective resource for QIP tasks such as RSP can be provided by simultaneous correlations in mutually unbiased bases.
Som Kanjilal, Aiman Khan, C. Jebarathinam, and Dipankar Home, Remote state preparation using correlations beyond discord, Phys. Rev. A 98, 062320 (2018)"