Observational Probes of Cosmology

18 November, 2020 | 4.30 PM(IST)

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Astrophysical observations in the last three decades have told us that we live in a preposterous universe with 70% dark energy, 25% cold dark matter and 5% ordinary baryons. I shall briefly recap the key observations which led us to this picture, as well highlight some recent developments which may call into question this standard picture. We then outline how we can make progress on probing some of these above questions (such as the nature of dark energy and dark matter) with a variety of observational probes (with a focus on galaxy clusters). I shall also discuss some of the technical "nuts and bolts" challenges involved in extracting the optimum Physics from these observations.

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Conservation of Quantum Information

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4:30 PM (IST), 21st October 2020

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The linearity and the unitarity are two fundamental tenets of quantum mechanics. Any consequence that follows from these two must be respected. We will discuss how the stronger no-cloning and the no-deleting theorems suggest that we cannot create quantum information nor can we destroy it. Further, we will discuss the implication of the no-hiding theorem which states that if information is lost from one of the system, it must move to some other part of the universe. Thus, the conservation of quantum information holds for all physical processes. Finally, we will discuss the no-masking theorem and its ramifications in quantum information.

Shadows, echoes and memory

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4:30 PM (IST), 30th September 2020

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Over the last few years, research in gravitational physics has shown how such commonplace notions like shadows, echoes and memory can be meaningful as well as important in appropriately chosen astrophysical scenarios. The talk will provide an introduction to the basics of these three phenomena with a focus on current research and open issues.

Anyon condensation and (some of) it's applications

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4 PM (IST), 21st July 2020

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I will review the notion of "anyon condensation" in 2+1 dimensional topological order.
I will give a very simple introduction to how it is naturally described in tensor category theory, and the connections it has with several other important areas in physics. Most notably, it describes topological gapped boundaries and interfaces between topological orders. Then, they are related to modular invariant CFT's and their topological line operators. Most recently, it is realized that it plays an interesting role in understanding the notion of "algebraic" symmetries.

Quantum devices using systems with impurities

14:00 (IST), 3rd July 2020

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The fledgling field of quantum information and computation boasts several quantum-enabled devices that outperform their classical counterparts, as also quantum protocols and phenomena without classical analogs. We will discuss some such situations when the corresponding system is inflicted with impurities and noise in different forms. In particular, we will discuss the effect of impurities on the behavior of population inversion and entanglement sudden death in single and double Jaynes Cummings models. We will also talk about localization-like effects due to disorder insertion in quantum random walks. Time permitting, we can also examine the effect of disorder on the behavior of entanglement in certain quantum many-body systems.

Simulating the quantum world with laser-cooled trapped ions

06:30 PM (IST), 19th June 2020

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Can physics be simulated by a universal computer? Classical physics, maybe; but what about quantum physics? Feynman's suggestion to build a computer out of quantum mechanical elements is now an active area of experimental research. While a large-scale quantum computer is perhaps not practical for a long time to come, noisy intermediate-scale quantum (NISQ) devices with up to a few dozens of quantum-bits are already a reality. In this talk, I will give an overview of quantum information processing with laser-cooled trapped ions, and describe our efforts at the University of Waterloo to build quantum simulators as well as a shared, multi-user, open-access quantum computer for the academic community.

Conformal invariance in physics

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4 PM (IST), 28th May 2020

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I will present a fairly broad survey of conformal symmetry in two dimensions and outline its application to various physical problems ranging from statistical systems to quantum Hall physics to topological quantum computing to 3d gravity. Thereafter I will survey some approaches to the classification of conformal-invariant field theories and recent results in this area.