Events

Emergence of quantum information science has led to a paradigm shift in communication systems. In the past couple of decades, quantum information processing tasks like quantum cryptography, dense coding, quantum teleportation etc. have been shown to have advantages over their classical counterparts and have also been successfully implemented in laboratories.

Dusan Sarenac: Far-field moire neutron interferometry

In this talk I will present our work on developing far-field moire neutron interferometry at the National Institute of Standards and Technology's Center for Neutron Research. We have successfully built a two phase-grating moire interferometer and employed it for phase contrast imaging.

Angus Kan, Wesleyan University

The study of charged particles dynamics in a Paul trap is the foundation of its wide-ranging applications, including analyzing proteins, determining isotope ratios, and constructing a quantum computer. However, in the simplest case of two-particle dynamics, there remains a controversy on whether a two-ion planar crystal undergoes an order-to-chaos transition at a critical, well-defined trap parameter value. Via analytical and numerical investigation of the Mathieu-Coulomb equations, I show that the transition does not exist.

Anqi Huang - IQC

Quantum key distribution (QKD) is able to achieve information-theoretic security in principle. However, in practice, imperfect devices threaten the security of quantum cryptographic systems. As a promising countermeasure against practical attacks, measurement-device-independent (MDI) QKD is immune to all detector side-channel attacks. Nevertheless, there are some limitations of the MDI QKD protocol. To overcome the technical limitations of MDI QKD, I scrutinized and evaluated other two countermeasures against imperfect detections.

Thomas Aref, University of Illinois at Urbana-Champaign

My research focuses on probing superconducting quantum bits or qubits with acoustic radiation in the form of surface acoustic waves (SAWs). This allows the investigation of sound interacting with artificial atoms on a quantum mechanical level, i.e. quantum acoustics with traveling phonons. We can then reproduce findings from quantum optics with sound taking over the role of light, highlighting the similarities between phonons and photons.

Yiwen Chu - Yale University

The ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies. Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions to superconducting resonators. Recently, there have been many efforts to extend these demonstrations to the motion of complex, macroscopic objects.

Sangil Kwon: Phase in Superfluids and Spontaneously Broken Gauge Symmetry

It is often said that superfluids (including superconductors) can be described by a macroscopic quantum wavefunction and their phase transition can be understood based on the concept of spontaneously broken gauge symmetry. This statement is not, however, trivial at all. In this seminar, I will discuss some conceptual problems that stem from applying the concept of spontaneously broken gauge symmetry to superfluids.

Gilles Brassard, Université de Montréal

It is generally believed that experimental violations of Bell's inequalities (especially the recent so-called loophole-free experiments) provide evidence that quantum theory cannot be both local and realistic. We demonstrate to the contrary that all reversible-dynamics no-signalling operational theories (including unitary quantum theory) can be given a local-realistic interpretation.

Gerard Valentí Rojas - The Institute of Photonic Sciences, Spain

The laws of quantum mechanics have helped scientists to unravel the behaviour of nature at its most fundamental scales. However, quantum phenomena are often difficult to understand and simulations have historically provided a useful framework for their study. Nevertheless, when dealing with large quantum systems or real-time dynamics, the computational cost of numerical simulations can become unfeasible.

Peter Zoller - University of Innsbruck

We start with an overview of chiral quantum optics as quantum light-atom interfaces with broken left- right symmetry and associated quantum optical phenomena and applications. While chiral quantum optics is traditionally discussed in context of nano-photonics and nano fibers , we propose here a novel ‘free-space’ chiral quantum optics realized as atoms in free space coupled to a ‘few-atom’ quantum antenna. In particular, we discuss free space photonic quantum links between atoms (qubits) equipped with sending and receiving quantum antennas.