Physics

In this talk we will discuss the notion of thermality for quantum field theories in curved spacetimes, and how it relates to the Unruh effect and Hawking radiation. Then we will argue that particle detectors are physical systems which can act as thermometers, thermalizing to the temperature of the field. We will show that any non-relativistic quantum system undergoing appropriate trajectories can probe the field’s temperature, regardless of how they are coupled to the field.

Quantum error correction is necessary for scalable quantum computation. Topological quantum error correcting codes have exceptional properties that make them ideal for future experiments. Massive gains can be achieved if the code is optimized for the noise, which we demonstrate for some 3D codes under biased noise.

Process matrices are objects that comprehensively describe multipartite quantum processes and their correlations. These matrices simultaneously play the roles of quantum states and quantum channels, and, to ensure a well-defined probability distribution, they are constrained to be positive. A key advantage of the process matrix formalism is that it can be used to describe processes with an indefinite causal order, which obey local quantum mechanics but cannot take place within a global causal structure. In this talk, i will give a complete introduction to the process matrix formalism and share preliminary results about the geometric positivity constraints of a special class of parameterised process matrices.

A fundamental area in statistical analysis is the study of which causal structures connecting the events of interest can explain the correlations that are observed between them. This is done through the falsification of invalid causal models. Our causal structure might posit the existence of hidden (unobserved) causes between the observed events. For example, if we see a positive correlation between the numbers of shark attacks and ice cream sales, we do not expect to explain it by a direct causal influence between these two things; instead, there should be a hidden common cause (for example, the Summer) that explains the correlation. Physicists also have a vested interest in falsifying causal hypotheses involving hidden variables. Bell's Theorem, for example, highlights the failure of many such classical causal hypotheses to explain the correlations predicted by quantum theory. In the scenario which Bell considered, if instead of treating the unobserved causes of classical random variables we treat them as potentially entangled quantum systems, we can explain a strictly larger set of correlations. Out project explores a simple but difficult question: In what other causal structures this also happens? In other words, for a given causal hypothesis, would the set of correlations it can explain expand if we relax our assumptions regarding posited unobservable systems to allow for shared entanglement? By a series of tricks developed during the PSI Winter School, we found that allowing for quantum causes makes an operational difference in a large number of causal hypotheses involving four observed variables. This work is of general interest as it generalizes Bell's Theorem: it exposes (qualitatively novel?!) advantages afforded by quantum theory over classical models. Bell's Theorem has proven crucially insightful in efforts to provide a causal accounting of quantum theory, and has inspired a plethora of quantum information theoretic protocols; similar dividends may be implicitly suggested by this work.

Seventy years ago, two radio engineers emerged from the frenzy of World War II and entered the new field of radio astronomy.Robert Hanbury Brown and Richard Twiss developed an entirely new instrument and technique, based on "correlated noise,"to measure theangular radius of previously unresolvable stars. Initially greeted with skepticism, their work led directly to the birth of quantum optics.  At nearly the same time, Goldhaber et al discovered a tiny unexpected correlation in the first true particle physics experiments; until recently, the "GGLP" effect played a minor role in particle physics.  It would take another 15 years until the connection between these apparently disparate phenomena was realized by Shuryak and others around 1976, just as the new field of heavy ion physics was emerging.  Thus did Hanbury Brown's discovery give birth to femtoscopy, the most direct method to probe space and time at the scales of 1e-15 meter and 1e-22 second.  I will discussthe structures and insights that femtoscopy has revealed in ultra-relativistic ion collisions at RHIC and the LHC and their rolein establishing the hydrodynamic nature of the quark-gluon plasma.  I will briefly discuss current progress to bring a high-energy physics approach to telescope arrays and relaunch stellar intensity interferometry with fast digital electronics and massive computing.

Type Ia Supernovae (SN Ia) are a central pillar of cosmology that is vital to the adoption of the LambdaCDM “Standard Model of cosmology”, but they also uniquely elucidate persistent gaps in the theory. I will detail recent monumental leaps in progress of SNIa analyses that have culminated in the Pantheon+ cosmological analysis which is an improvement of a factor of 2 over its predecessor and that is the current best measurement of the dominant energy density components of the universe and the current best constraint on extensions to LambdaCDM including evolving dark energy. Additionally I will discuss the recent Pantheon+SH0ES constraints of the local value of the Hubble Constant that are now even more robust to systematics and that have now crossed the significant 5 sigma threshold of discrepancy when compared to that of Planck+LambdaCDM. Lastly, I will summarize the lessons learned over the last 5 years and their impact on future SN Ia surveys.  

Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g., quantum engines and the thermodynamic value of coherences). I will overview how quantum information theory is being used to revolutionize thermodynamics in quantum steampunk, named for the steampunk genre of literature, art, and cinema that juxtaposes futuristic technologies with 19th-century settings.

Zoom Link: https://pitp.zoom.us/j/92454766615?pwd=QzZXMnYwN3ZZOTE5RzZEcHp6TkhMdz09

The patent system is designed to help innovators protect their intellectual property. In this colloquium, we will discuss logistical and strategic aspects of the patent process, to help you better understand how to leverage the patent system. Topics will include the anatomy of a patent, deadlines and procedural steps for filing patent applications, and strategic considerations in developing the claims and other components of a patent application.

Zoom Link: https://pitp.zoom.us/j/91402107798?pwd=UDRQV0IvY3JEUkVJeC9QR3JXVjZSdz09