Events

Extended Learning Graphs for Triangle Finding

Mathieu Lauriere, New York University, Shanghai

In this talk we present new quantum algorithms for Triangle Finding improving its best previously known quantum query complexities for both dense and spare instances. For dense graphs on n vertices, we get a query complexity of O(n^{5/4}) without any of the extra logarithmic factors present in the previous algorithm of Le Gall [FOCS’14]. For sparse graphs we also improve some of the results obtained by Le Gall and Nakajima [ISAAC’15].

Vincent Russo of the Department of Computer Science is defending his thesis:

Extended nonlocal games

Vincent is supervised by IQC faculty members John Watrous and Michele Mosca.

Research with very cold and ultra-cold neutrons at the Institute Laue Langevin in Grenoble

Peter Geltenbort, Institute Laue Langevin, Grenoble

Due to their outstanding property to be storable and hence observable for long periods of time (several hundreds of seconds) in suitable material or magnetic traps, ultra-cold neutrons (UCN) with energies around 100 neV are an unique tool to study fundamental properties of the free neutron, like its beta-decay lifetime, its electric dipole moment and its wave properties.

Entanglement in a synthetic quantum magnet made of hundreds of trapped ions

Justin Bohnet, National Institute of Standards and Technology, Boulder

Entanglement between individual quantum objects exponentially increases the complexity of quantum many-body systems, such that models with more than 40 quantum bits cannot be fully studied using conventional techniques on classical computers. To make progress at this frontier of physics, Feynman’s pioneering ideas of quantum computation and quantum simulation are now being pursued in a wide variety of well-controlled platforms.

Quantum experiments exploiting the radiation pressure interaction between light and matter

Simon Gröblacher, Delft University of Technology

Mechanical oscillators coupled to light via the radiation pressure force have attracted significant attention over the past years for allowing tests of quantum physics with massive objects and for their potential use in quantum information processing. Recently demonstrated quantum experiments include entanglement and squeezing of both the mechanical and the optical mode.

Quantum error-correction in black holes

Beni Yoshida, Perimeter Institute

It is commonly believed that quantum information is not lost in a black hole. Instead, it is encoded into non-local degrees of freedom in some clever way; like a quantum error-correcting code. In this talk, I will discuss recent attempts to resolve some paradoxes in quantum gravity by using the theory of quantum error-correction.

Atomic scale study of Dirac materials: graphene and topological insulator (Bi2Se3)

Ying Liu

Graphene and topological insulator Bi2Se3 are newly discovered Dirac materials with exotic physical and electronic properties. The molecular beam epitaxy (MBE) and in situ characterization at atomic scale of the materials are demonstrated in this talk[1][2]. Artificial defects of graphene are created by Ar for extending its functions. Their structural, electronic properties and charge state were studied by scanning tunneling microscopy (STM) and q-plus atomic force microscopy (q-plus AFM ), respectively.

Quantum entanglement for precision sensing with atoms and light

Onur Hosten, Stanford University

In the last decades, advances in the level of precision in controlling atomic and optical systems opened up the low-energy precision frontier to fundamental physics tests in addition to yielding new applied sensing technologies. In this talk I will focus on our experiments with cold atoms highlighting some of the most recent developments in the prospect of using quantum entanglement to further improve the precision of atomic and optical sensors.

An inversion-symmetry-broken order inside the pseudogap region of a cuprate revealed by optical second harmonic generation

Liuyan Zhao, University of Michigan

The phase diagram of cuprate high-temperature superconductors features an enigmatic pseudogap region that is characterized by a partial suppression of low-energy electronic excitations. In order to understand its microscopic nature, it is imperative to identify the full symmetries both prior to and within the pseudogap region. In this talk, I will describe our experimental results of symmetry properties on YBa2Cu3Oy across a wide temperature and doping range using a recently developed nonlinear optical rotational anisotropy technique.

The mathematics of non-local games

William Slofstra, Institute for Quantum Computing

Non-local games are an important subject in quantum information. They provide relatively simple experimental scenarios for testing the axioms of quantum mechanics, and have been proposed for other practical applications, especially in device-independent cryptography. However, we do not know how to answer many of the basic mathematical questions about non-local games.