Staff

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.

Rakesh Tiwari, McGill University

Quantum phenomena have the potential to speed up the solution of hard optimization problems. For example quantum annealing, based on the quantum tunnelling effect, has recently been shown to scale exponentially better with system size as compared with classical simulated annealing. However, current realizations of quantum annealers with superconducting qubits face two major challenges. First, the connectivity between the qubits is limited, excluding many optimization problems from a direct implementation.

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.

APS March Meeting Student Practice Talk Session

Pavithran Iyer, Université de Sherbrooke

Arbitrary precision quantum control of qubit systems appears to be unobtainable due to environmental influences that manifest themselves as errors in a quantum algorithm. Errors modelled by the probabilistic application of Pauli operators during the computation are convenient for analytical proofs and classical simulation but the level of accuracy of such a model depends on the quantumness of the error source.

Feihu Xu, University of Science and Technology of China

Every time you take a photo, photons strike different parts of your image sensor in different quantities. In daytime, your sensor detects more than a billion photons, which are more than 1000 photons per pixel for a basic one-megapixel camera. Can you take a photo with one photon per pixel? I will address how to perform accurate imaging at a light level of one photon per pixel.

David Gosset, IBM TJ Watson Research Center

There is strong evidence that a sufficiently large fault-tolerant quantum computer would solve certain computational problems exponentially faster than any classical computer. How can quantum algorithms and complexity theory help guide the way forward in our current era of small and noisy quantum computers?

Colloquium featuring Karl Jansen - NIC/DESY Zeuthen, Germany

The strong interaction of quarks and gluons is described theoretically within the framework of Quantum Chromodynamics (QCD). The most promising way to evaluate QCD for all energy ranges is to formulate the theory on a 4 dimensional Euclidean space-time grid, which allows for numerical simulations on state of the art supercomputers. We will review the status of lattice QCD calculations providing examples such as the hadron spectrum and the inner structure of nucleons.

Quantum mechanics reveals that at its core, the world is not as it seems – it is far more interesting.
 
In the quantum world, outcomes are counter-intuitive, differing from what we expect based on our everyday experiences. The particle physicist Richard Feynman remarked that this means we seem to have to walk “a logical tightrope” when we talk about a quantum system.  
 

Jiawei Ji - The University of Calgary

Quantum circuits based only on matchgates are able to perform non-trivial (but not universal) quantum algorithms. Because matchgates can be mapped to non-interacting fermions, these circuits can be efficiently simulated on a classical computer. One can perform universal quantum computation by adding any non-matchgate parity-preserving gate, implying that interacting fermions are natural candidates for universal quantum computation within the circuit model.