Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.
Recordings of events in these areas are all available and On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.
Trapped ions are among the most advanced technology platforms for quantum information processing, in particular quantum simulation. However, ions are most readily trapped as a linear chain in radio-frequency traps, limiting their use to simulate higher dimensional quantum systems. In this talk, I'll describe an analog and an analog-digital hybrid [1] quantum simulation protocols to simulate programmable 2D and 3D spin models in a linear ion chain, by manipulating phonon-mediated long-ranged interactions between ion spins.
Coherent errors in a quantum system can, in principle, build up much more rapidly than incoherent errors, accumulating as the square of the number of qubits in the system rather than linearly. I will characterize the types of channels that can exhibit such behavior and present a simple protocol that can detect and characterize coherent errors whenever they are present, no matter what their nature. This allows us to identify coherent errors in gates and measurements to within a constant fraction of the maximum possible sensitivity to such errors.
Tensor networks are powerful computational tools, widely used in condensed matter physics, and increasingly in high-energy physics, with promising applications to machine learning problems. Developed in collaboration with Google and X, we present TensorNetwork: a new software package that makes it easier to code tensor network algorithms and, by using a framework like TensorFlow as a backend, to accelerate computations using specialized hardware (GPUs, TPUs) and integrate tensor networks into machine-learning projects.
I will present an efficient variational approach for preparing highly entangled pure states as well as thermofield double states on a quantum computer. The latter, in addition to being of interest in the holographic correspondence, enables an alternative approach for simulating thermal states without an external heat bath.
I will describe a proposal to simulate MERA on Google's 72 qubit NISQ device known as Bristlecone, and explain how it can be the basis for simulating inflation in an early universe. Other applications of this proposal include benchmarking of the NISQ device, hybrid classical quantum optimizations and quantum machine learning.
Fracton order is a new kind of phase of matter which is similar to topological order, except its excitations have mobility constraints. The excitations are bound to various n-dimensional surfaces with exotic fusion rules that determine how excitations on intersecting surfaces can combine.
New physics in the neutrino sector might be necessary to address anomalies between different neutrino oscillation experiments. Intriguingly, it also offers a possible solution to the discrepant cosmological measurements of H_0.
Modified gravity theories typically feature numerous additional parameters and functions as compared to general relativity, which are unmotivated by observations and challenging to meaningfully constrain. We instead propose a new theory of gravity with the startling property of having *fewer* degrees of freedom than general relativity with a cosmological constant, by invoking a duality property within a first-order formulation that supports torsion.
I shall analyze three specific general-relativistic problems in which gravitomagnetism plays important role: the dragging of magnetic fields around rotating black holes, dragging inside a collapsing slowly rotating spherical shell of dust, compared with the dragging by rotating gravitational waves (CQG 34, 205006 (2017), Phys. Rev. D 85 124003, (2012) etc). I shall also briefly show how "instantaneous Machian gauges“ can be useful in the cosmological perturbation theory (Phys. Rev. D 76, 063501 (2007)).
We derive an effective Hamiltonian constraint for the Schwarzschild geometry starting from the full loop quantum gravity Hamiltonian constraint and computing its expectation value on coherent states sharply peaked around a spherically symmetric geometry. We use this effective Hamiltonian to study the interior region of a Schwarzschild black hole, where a homogeneous foliation is available.
Check back for details on the next lecture in Perimeter's Public Lectures Series