Events

SIC-POVMs and algebraic number theory

John Yard, Institute for Quantum Computing

SIC-POVMs (Symmetric Informationally Complete Positive Operator-Valued Measures) are certain extremal rank-1 projective measurements corresponding to maximal sets of complex equiangular lines as well as to minimal complex projective 2-designs. They are conjectured to exist in every finite-dimensional complex Hilbert space as orbits of generalized Pauli groups. 

Post-Quantum Key Exchange for the Internet and the Open Quantum Safe Project

Douglas Stebila, McMaster University

Most public key cryptography algorithms used on the Internet are based on mathematical problems which could be broken by large-scale quantum computers. This motivates the field of post-quantum cryptography, which aims to construct public key cryptosystems that are believed to be secure even against quantum computers. Since a future quantum computer could retroactively break the confidentiality of today's communications, it is important to begin transitioning public key encryption and key exchange to quantum-resistant algorithms.

Twisting the neutron wavefunction

Charles W. Clark, National Institute of Standards and Technology

Wave motions in water were already familiar in antiquity. The mathematical representation of waves in physics today is essentially the same as that first provided by d'Alembert and Euler in the mid-18th century. Yet it was only in the early 1990s that physicists managed to control a basic property of light waves: their capability of swirling around their own axis of propagation.

Public lecture by Charles W. Clark

Much of what we understand about the world comes from our eyes, which sense the colors from red to violet that are expressed in the rainbow.

John Donohue of the Department of Physics and Astronomy is defending his thesis:

Ultrafast manipulation of single photons using dispersion and sum-frequency generation

John is supervised by Associate Professor Kevin Resch.

Generation and Spectral Characterization of High-Purity Biphotons

Franco Wong, Massachusetts Institute of Technology

Spectrally factorable biphotons are highly desirable for many photonic quantum information processing tasks such as quantum computation, boson sampling, and quantum repeaters. We generate biphotons with spectral purity of 99%, the highest to date without any spectral filtering, by pulsed spontaneous parametric downconversion in a custom-fabricated PPKTP crystal under extended Gaussian phase-matching conditions.

Cybersecurity is Hard. Up for a Challenge?

Mark McArdle, eSentire

Pure technology approaches to cybersecurity consistently fail to prevent hackers from breaching networks and systems. The pursuit of a pure technology solution to cybersecurity is going to require significant breakthroughs in AI and machine learning. Come join a discussion about why cybersecurity is such a hard problem and review some promising areas of research that may bring positive changes.

Efficient Quantum Algorithms for Simulating Lindblad Evolution

Chunhao Wang

The Lindblad equation is the natural generalization to open systems of the Schrödinger equation. We give a quantum algorithm for simulating the evolution of an n-qubit system under the Lindblad equation with local terms. The gate cost of the algorithm is O(mTlog^2(T/\epsilon)/loglog(T/\epsilon)), where T is the evolution time, \epsilon is the precision of the output state, and m is the number of local terms occurring in the equation.

Graphs and Multi-mode Coupling: How to build a programmable, directional parametric amplifier

Jose Aumentado, National Institute of Standards and Technology, Boulder

Parametric amplification is a big deal these days, especially for research in superconducting quantum information. This is because, in principle, parametric amplifiers can amplify a signal while adding the minimum amount of noise that quantum mechanics allows. In practice, the situation is a little more complicated and the practical measurement chains can degrade this ideal performance.

Entanglement and Purcell Effects in Systems for Quantum Information and Sensing

Stephen K. Gray, Argonne National Laboratory

I discuss how to propagate the quantum mechanical density matrix, including dephasing, spontaneous emission and dissipation for systems relevant to quantum information and sensing. Two applications are then presented. In the first example, a plasmonic system is coupled to quantum dots. The plasmonic system could be a single metal nanoparticle or an array of metal nanoparticles and can be viewed as an optical resonator.