Spring 2021

Analog quantum algorithms are formulated in terms of Hamiltonians rather than unitary gates and include quantum adiabatic computing, quantum annealing, and the quantum approximate optimization algorithm (QAOA).  These algorithms are promising candidates for near-term quantum applications, but they often require fine tuning via the annealing schedule or variational parameters.  In this work we connect all these algorithms to the optimal analog procedure.  Notably, we explore how the optimal procedure approaches a smooth adiabatic procedure but with a superposed oscillatory pattern that can b

Dissertation Committee Chair: Chris Monroe

Dissertation Committee Chair: Prof. Christopher Monroe
Committee: 
Prof. Norbert Linke
Prof. Alicia Kollár
Prof. Vladimir Manucharyan
Prof. Christopher Jarzynski
Abstract:
Quantum computers promise to solve models of important physical processes, optimize complex cost functions, and challenge cryptography in ways that are intractable using current computers. In order to achieve these promises, quantum computers must both increase in size and decrease error rates.

 Competition between unitary dynamics that scrambles quantum information non-locally and local measurements that probe and collapse the quantum state can result in a measurement induced entanglement phase transition. Here we study this phenomenon in an all-to-all Brownian hybrid circuit model of qubits that is analytically tractable. A part of the system is initially entangled with a reference which remains mixed at low measurement rates but is purified at high measurement rates.

Sankar Das Sarma, UMD10:00 AM - 10:55 AM”Searching for Topological Majorana Zero Modes”
Tadashi Machida, RIKEN Center for Emergent Matter Science11:00 AM - 11:55 AM"Searching for Majorana quasiparticle in Iron-based superconductors"
Erik Bakkers,  Eindhoven University of Technology12:00 PM - 12:55 PM“Reducing disorder in Semiconductor/supercondu ctor nanowires”

Quantum metrology, which studies parameter estimation in quantum systems, has many important applications in science and technology, ranging from frequency spectroscopy to gravitational wave detection. Quantum mechanics imposes a fundamental limit on the estimation precision, called the Heisenberg limit, which is achievable in noiseless quantum systems, but is in general not for noisy systems. This talk is a summary of some recent works by the speaker and collaborators on quantum metrology enhanced by quantum error correction.

Dissertation Committee:
Professor Christopher Monroe, Chair/Advisor
professor Mohammad Hafezi
professor Edo Waks
Professor Alexey Gorshkov
Professor Lawrence Washington, Dean’s Representative
Professor Norbert Linke
Professor Xiaodi Wu
 
Abstract:

In many natural situations where the input consists of n quantum systems, each associated with a state space C^d, we are interested in problems that are symmetric under the permutation of the n systems as well as the application of the same unitary U to all n systems.

Marcus is recognised as a principal contributor to the emergence of diamond-based quantum technologies, including quantum microscopy, quantum computing and quantum communications. These technologies represent new paradigms of microscopy, computing and communications that have the potential to revolutionise many disciplines of science and technology. During this seminar Marcus will share more about how the industry can expand the vision for quantum computing.
Zoom Link: https://umd.zoom.us/j/95285740962

Immanuel Bloch, Ludwig-Maximilians University"Realizing and probing quantum matter using large scale quantum simulations"
Ignacio Cirac,Max Planck Institute of Quantum Optics“Simulations with analog and digital quantum computers”
Lieven Vandersypen, Delft University“Analog quantum simulating of Fermi-Hubbard physics using quantum dot arrays”