Talks

The primordial non-Gaussianity (PNG) is a key feature to screen various inflationary models and it is one of the main targets in the next generation galaxy surveys. In particular, the local-type of PNG makes the galaxy bias scale-dependent in large-scales, which is known as the scale-dependent bias, allowing to constrain the local-type PNG from galaxy surveys. In this talk, I will present the galaxy shape correlation, called the ``intrinsic alignment'', can explore the angular-dependent PNG. Using N-body simulations, we show the angular-dependent PNG induces the scale-dependent bias in the intrinsic alignment, just as the angular-independent PNG leads to the scale-dependent bias in the galaxy number density correlation. By combining photometric and spectroscopic surveys to measure the intrinsic alignment, future galaxy surveys are potentially capable of constraining the angular-dependent PNG better than CMB experiments.

How to deal with diffeomorphism symmetries is one of the difficult problems in general relativity. Because of the diffeomorphism symmetries, we need to consider diffeomorphism invariant operators and gravitational dressing. In this work, we consider a special gravitational dressing which is to locate the operator by shooting geodesic from the spatial boundary. We try to use Peierls bracket to study the commutator between this gravitational dressing operator and the ADM energy operator. We found the ADM energy increase/decrease when the extra created out-going particle is in front of/behind the event horizon. Our result strengthens the Marolf-Polchinski firewall argument in some sense. In the talk, I will first briefly review the Peierls bracket, which is a linear response interpretation of bracket computation in covariant phase space formalism. We also illustrate the Peierls bracket with several examples. After that, we use Peierls bracket to study the Hamiltonian flow of the gravitational dressing operator, from which we can read out the commutator between the gravitational dressing operator with the ADM energy operator.

The entanglement pattern of a quantum many-body system can be characterized by quasiparticles and emergent gauge fields, much like those found in Maxwell's theory. My talk begins with the basic aspects of symmetry fractionalization and emergent gauge fields in strongly correlated systems. I will further extend this paradigm into a new type of quantum many-body state, dubbed "fracton phase," from a quantum melting transition of plaquette paramagnetic crystals. These exotic states contain fractionalized sub-dimensional quasiparticles with constraint motion and emergent higher-rank gauge fields. Such constraint dynamics of the quasiparticles bring about an intriguing Bose metal phase with quasi-long range order and yields non-local quantum entanglement. In particular, the key peculiarities of this phase is the UV/IR mixing, where the short wavelength physics controls the low energy theory and hence challenges the standard notion of the renormalization group perspective.

If time is described by a fundamental process rather than a coordinate, it

interacts with any physical system that evolves in time. The resulting
dynamics has recently been shown to be consistent provided the fundamental
period of the time system is sufficiently small. A strong upper bound T_C
< 10^{-33}s of the fundamental period of time, several orders of magnitude
below any direct time measurement, can be obtained from bounds on
dynamical variations of the period of a lab system evolving in time.
Possible cosmological implications will be discussed.