Seminar

Andrew N. Cleland, University of Chicago

Superconducting qubits offer excellent prospects for manipulating quantum information, with good qubit lifetimes, high fidelity single- and two-qubit gates, and straightforward scalability (admittedly with multi-dimensional interconnect challenges). One interesting route for experimental development is the exploration of hybrid systems, i.e. coupling superconducting qubits to other systems.

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.

Tarun Patel: Photocurrent imaging of charge density wave transitions in ultrathin 1T-TaS2  

1T-TaS2 is a layered van-der Waals material which shows multiple charge density wave (CDW) transitions as a function of temperature. Ultrathin flakes fabricated by mechanical exfoliation and protected from oxidation with h-BN capping in inert atmosphere have been shown to retain these transitions.

Ke He, Tsinghua University

The quantum anomalous Hall (QAH) effect is a quantum Hall effect induced by spontaneous magnetization instead of an external magnetic field. The effect occurs in two-dimensional (2D) insulators with topologically nontrivial electronic band structure which is characterized by a non-zero Chern number. The experimental observation of the QAH effect in thin films of magnetically doped (Bi,Sb)2Te3 topological insulators (TIs) paves the way for practical applications of dissipationless quantum Hall edge states.

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.

Brandon Buonacorsi - Modeling the Exchange Interaction in Silicon Quantum Dots

Silicon metal-oxide-semiconductor field effect transistor (MOSFET) quantum dots are promising candidates for scalable quantum computing using electron spin qubits due to their long coherence times, compact size, and ease of integration into existing fabrication technologies.  I will introduce how we fabricate these devices and describe the experimental characterizations we do to check the stability and tunability of our quantum dots.  In a double quantum dot device, two qubit gates are realized

Pan Zheng

Creating and Measuring Two-Mode Cat States

IQC/Physics Special Seminar - Loren Swenson, D-Wave Systems

I will introduce quantum annealing as a technique for harnessing quantum mechanics to solve hard problems. The design of a quantum annealing processor based on superconducting flux qubits, some of the challenges we have encountered in constructing it, and measurements confirming the role of quantum mechanics in such processors will be presented. Finally, I will briefly discuss recent benchmarking and simulation results using the D-Wave 2000Q processor.

Colloquium: Xiaoting Wang, University of Electronic Science and Technology of China 

Quantum information processing (QIP) has been identified as one of the key future technologies that are crucial for communication, cryptography, computing, complex-system simulation, metrology, artificial intelligence and national security. Quantum control, on the other hand, provides a powerful tool to analyze and improve the physical performances of different QIP devices.

Pardis Sahafi - London, Royal Holloway College

Semiconductor electron pump devices have shown promise for current standards due to their high accuracy current transport [1]. Further to this, at higher fields and frequencies these pumps demonstrate excitation states corresponding to energies in the microwave range [2]. This suggests possible applications in microwave and THz photonics, an emerging field with applications spanning from quantum information processing to medical imaging.