Events

Wavelength selective thermal emitters using nitride quantum wells and photonic crystals

Dr. Dongyeon Daniel Kang, Kyoto University

Wavelength selective thermal emitters are highly desired for the development of the compact/energy-efficient spectroscopic sensing systems capable of detecting various gases such as CO_x, CH₄, and NO_x, which are strongly needed in environmental science, medical care, and other industrial applications. In addition, for the latter applications, dynamic control of thermal emission intensity is important for such emitters because synchronous detection can increase the signal-to-noise ratio significantly.

PhD Seminar: Olivia Di Matteo

Quantum random-access memories (qRAM) are required by numerous quantum algorithms. In many cases, qRAM queries are the limiting factor in the implementation of these algorithms. In the limit of a large number of queries, there will be a massive resource overhead, as in this regime it is not possible to bypass the need for active error correction. In this talk, I will present our work towards quantifying this overhead. We will explore a variety of different qRAM circuits designed to query classical bits in superposition.

Stacey Jeffery, QuSoft, Research Centre for Quantum Software

A random walk on a graph, P, with marked vertex set M, finds a marked vertex using a O(HT(P,M)) steps of the walk, where HT(P,M) is the hitting time. Previous quantum algorithms could detect the presence of a marked vertex in O(sqrt{HT(P,M)}) steps, or find a marked vertex in O(sqrt{HT(P,M)}) steps if M contained at most one vertex, but the case of finding in the presence of multiple marked vertices was left as an open problem.

Stefan Frick, University of Bristol, UK

Rangefinding has many applications in navigation, civil engineer, construction, military, surveillance and security. Most commonly rangefinders estimate the distance to an object by measuring the time of flight of light for the journey to and returning from the target. Conventional techniques use lasers for illumination in state of the art rangefinding systems. However, the particular state of light lasers produce makes them easy to detect.

Giovanni Fanchini, Western University

In this talk, we will review the use of thin films of organic polyradicals – organic polymers with one unpaired electron per monomer [1] – for memory devices and other applications. Although memory devices based on radical polymers have been often proposed, their stability was frequently limited to a few writing cycles, despite the excellent quality of the active layer.

Alexander Belovs, University of Latvia

This talk reflects on recent research in progress with Andras Gilyen. Over the years, there have been a number of papers dealing with quantum algorithms testing some properties of classical probability distributions. Our goal is to understand what is the right way for quantum algorithms to access the distribution. There is a number of possible models, and we analyse their mutual strength.

Frederic Magniez, Université Paris Diderot

We describe a new quantum paradigm, that we call Quantum Chebyshev’s inequality, to approximate with relative error the mean of any random variable with a number of quantum samples that is linear in the ratio of the square root of the variance to the mean. Classically the dependency is quadratic. To illustrate this method, we apply it to the approximation of frequency moments in the multi-pass streaming model, and to the approximation of the number of edges and triangles in the quantum graph query access model.

Spontaneous Raman emission in cold atoms inside a hollow-core waveguide

Taehyun Yoon, Institute for Quantum Computing

Cold atoms confined inside hollow-core waveguides enable strong-matter interactions, thus offer a unique platform for studies of quantum and non-linear optics. We developed an experimental system that traps cesium atoms in a magneto optical trap (MOT) and loads these atoms into a hollow core photonic crystal fiber using a dipole trap at cesium magic wavelength (935 nm), which removes the AC-Stark shift of the optical transition and suppresses the inhomogeneous broadening.

Ken Andersen, Neutron Instruments Division, European Spallation Source ERIC

The European Spallation Source is currently under construction in Lund, Sweden. It is designed to provide world-leading performance, with instruments optimized for the long-pulse time structure of the facility, making full use of the world’s brightest neutron beams for the study of materials ranging from biological systems and soft matter to engineering materials, structural chemistry and magnetism.

Fabrication and Growth of 111 SiNWs for Mechanical Spin-Detection

Pardis Sahafi, Institute for Quantum Computing

In our group, vertical Si nanowires grown on a 111 surface are used for force detection in nanoscale NMR and ESR. These measurements require a very long (20 µm) and minimally tapered vertical Si nanowires, to be used as nano-mechanical oscillators with a high quality factor (Q ~ 10⁴).