N/A

Free lunch served at 11:45

Is Brooklyn expanding?

Alan Turing was fascinated by the possible variation of natural laws in time. There is just a hint of this in his paper, "Computing Machinery and Intelligence," the source of the famous phrase "the imitation game." The subject, long at the intersection of science and philosophy, has recently started to become of practical interest.

Free lunch served at 11:45

Textbook conceptions of light-matter interactions have been challenged by two recent material

advances - the development of metamaterials and the introduction of parity-time (PT)-symmetric

media. Metamaterials allow considerable control over the electric and magnetic fields of light, so

that the permittivity, permeability, and refractive index can be tuned throughout positive, negative,

and near-zero values. Metamaterials have enabled negative refraction, optical lensing below the

We introduce a new method for proving limitations on the ability of semidefinite programs (SDPs) to approximately solve optimization problems. We use this to show specifically that SDPs have limited ability to approximate two particularly important sets in quantum information theory:

1. The set of separable (i.e. unentangled) states.

2. The set of quantum correlations; i.e. conditional probability distributions achievable with local measurements on a shared entangled state.

Fault-tolerant quantum computation (FTQC) can be done in principle: the threshold theorems show that, for sufficiently low error rates, it is possible to do quantum computations of arbitrary size. However, current schemes that allow such scaling--using concatenated or surface codes--require very large overhead to achieve quantum computation at realistic error rates. One approach to reduce this overhead is to encode multiple logical qubits in a single code block.

Every time the release button of a digital camera is pressed, several megabytes of raw data are recorded. But the size of a typical jpeg output file is only 10% of that. What a waste! Can't we design a process which records only the relevant 10% of the data to begin with?

Considerable work has recently been directed toward developing resource theories of quantum coherence. In this talk I will review the general structure of such resource theories, and I will argue that all currently proposed basis-dependent approaches to quantum coherence fail to be physically consistent. That is, the “free” or “incoherent” operations defined within these frameworks ultimately require the consumption of quantum coherence to be physically implemented.

For the past twenty years, Tensor Network States (TNS) have been widely used to model the low energy sector of local Hamiltonians. Their success in doing so has led to the wide-held mantra that TNS of low bond dimension are the `only physical states' of natural condensed matter systems. However, given our experimental limitations to interact with such systems, it is not clear how this conjecture translates into any observable effect.

Gauge theories are the backbone of our current understanding of

fundamental interactions. While some of their aspects can be

understood using established perturbative techniques, the need for a

non-perturbative framework led to the lattice formulation of gauge

theories by Wilson in 1974. Since then, numerical simulations of

lattice gauge theories have celebrated success in a plethora of

equilibrium phenomena, such as the ab initio calculation of the

low-energy hadron spectrum. However, classical simulations of gauge