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Monday, November 28, 2016 11:45 am - 11:45 am EST (GMT -05:00)

Theory of Quantum Information and Computation: Chunhao Wang

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.

Monday, November 28, 2016 2:30 pm - 2:30 pm EST (GMT -05:00)

Colloquium: Jose Aumentado

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.

Tuesday, November 22, 2016 11:00 am - 11:00 am EST (GMT -05:00)

Seminar: Mark McArdle

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.

Thursday, November 17, 2016 3:30 pm - 3:30 pm EST (GMT -05:00)

Seminar: Franco Wong

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.

Tuesday, November 29, 2016 2:00 pm - 2:00 pm EST (GMT -05:00)

Seminar: Stephen K. Gray

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.

Monday, November 14, 2016 11:45 am - 11:45 am EST (GMT -05:00)

Theory of Quantum Information and Computation Seminar: Jon Yard

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. 

Thursday, November 10, 2016 11:00 am - 11:00 am EST (GMT -05:00)

Seminar: Juan Bermejo Vega

Contextuality as a resource for quantum computation

Juan Bermejo Vega

A central question in quantum computation is to identify the resources that are responsible for quantum speed-up. Quantum contextuality has been recently shown to be a resource for quantum computation with magic states for odd-prime dimensional qudits and two-dimensional systems with real wavefunctions. The phenomenon of state-independent contextuality poses a priori an obstruction to characterizing the case of regular qubits, the fundamental building block of quantum computation.

Monday, November 7, 2016 11:30 am - 11:30 am EST (GMT -05:00)

Theory of Quantum Information and Computation Seminar: Ashwin Nayak

A proof of the quantum data processing inequality with a combinatorial flavour

Ashwin Nayak, Institute for Quantum Computing

The quantum data processing inequality (equivalently, the strong sub-additivity of von Neumann entropy) is a cornerstone of quantum information theory.  It has been proven in numerous ways, each proof highlighting different aspects of the property.

Tuesday, November 15, 2016 11:00 am - 11:00 am EST (GMT -05:00)

Seminar: Charles W. Clark

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.

Monday, November 14, 2016 2:30 pm - 2:30 pm EST (GMT -05:00)

Colloquium: Douglas Stebila

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.