Talks

Information-theoretic insights have proven fruitful in many areas of quantum physics. But can the fundamental dynamics of quantum systems be derived from purely information-theoretic principles, without resorting to Hilbert space structures such as unitary evolution and self-adjoint observables? Here we provide a model where the dynamics originates from a condition of informational non-equilibrium, the deviation of the system’s state from a reference state associated to a field of identically prepared systems. Combining this idea with three basic information-theoretic principles, we derive a notion of energy that captures the main features of energy in quantum theory: it is observable, bounded from below, invariant under time-evolution, in one-to-one correspondence with the generator of the dynamics, and quantitatively related to the speed of state changes. Our results provide an information-theoretic reconstruction of the Mandelstam-Tamm bound on the speed of quantum evolutions, establishing a bridge between dynamical and information-theoretic notions.

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The mass and nature of neutrinos play an important role in theories beyond the standard model. The nuclear beta decay and double beta decay can provide the information on absolute effective mass of the neutrinos. At present, neutrinoless double beta decay (NDBD) is perhaps the only experiment that can tell us whether the neutrino is a Dirac or a Majorana particle. Given the significance of the NDBD, there is a widespread interest worldwide employing a variety of novel techniques. This talk will present a brief report of ongoing and proposed NDBD experiments and will highlight Indian efforts towards the feasibility study of search for NDBD in 124Sn.

I will first discuss how neutrino detectors such as SNO, SNO+, BOREXINO and MAJORANA Demonstrator can be repurposed to perform direct detection of dark matter in the Galactic halo via scattering and/or absorption. Then I will describe how "neutron shining through a wall" searches can be performed to smoke out dark sectors in neutrino facilities such as IsoDAR, COHERENT, SNS, and STEREO.

In this talk I show how simple ideas motivated from the Swampland program, lead to concrete predictions for our universe.  These include predictions for particle physics and cosmology.  I also discuss some experimental predictions for these ideas.

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Correlation functions are ubiquitous in quantum field theory, but their use in quantum gravity beyond perturbative and asymptotically flat regimes has been limited, due to difficulties with diffeomorphism invariance and the dynamical nature of geometry. We address these challenges in the context of nonperturbative quantum gravity, motivated by the goal of computing geometric correlators from first principles, as a possible window to early-universe cosmology. I will report on recent work in 2D Lorentzian quantum gravity, formulated in terms of causal dynamical triangulations, which demonstrates the feasibility of constructing and measuring manifestly diffeomorphism-invariant curvature correlators. I will discuss some unusual features of the connected correlators and new results on their behaviour in two dimensions, obtained with the help of Monte Carlo simulations.

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With the recent construction of quantum low-density parity-check (LDPC) codes with optimal asymptotic parameters, finding methods to perform low-overhead computation using those constructions has become a central problem of quantum error-correction. In particular, triorthogonal codes---which admit transversal non-Clifford operations---are of particular interest, but few examples of these codes are presently known. In our work, we introduce a new family of codes, the quantum rainbow codes, a generalization of pin codes and color codes, that can be constructed from any chain complex. When applied to the hypergraph product of three complexes, we show that those codes can implement transversal non-Clifford gates and have improved parameters compared to pin codes. Considering expander graphs with large girth as the input complexes, we can for instance obtain families of triorthogonal codes with parameters [[n,Θ(n^{2/3}),Θ(log(n))]].

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