Combining analog quantum simulation and digital quantum logic to characterize many-body systems
Abstract
Quantum entanglement allows exponentially more configurations for a given number of particles or bits when compared to the same number of classical objects. This complexity is of both fundamental and practical interest. Over the last 20 years, significant progress has been made in developing both theoretical understanding and practical physical realizations of large quantum system, in two distinct areas. Quantum simulation aims to create complex quantum systems that controllably mimic the behavior of fundamental particles, to understand models that are computationally unsolvable by other means. On the other hand, the field of quantum information science aims to build devices capable of storing and processing states of quantum information, for faster computing, more secure communications and more precise metrology. These fields share an important goal: understanding and characterizing the states and dynamics of large quantum systems. However, the amount of information necessary to fully describe quantum states grows exponentially with the size of the system. As a practical matter, complete reconstruction of these states requires exponentially many copies and measurements, which is impractical for large systems. As a fundamental matter, even if this information could be obtained, it would be incomprehensible. There are two ways of dealing with this complexity. The first is to recognize that there are subspaces of the full Hilbert space that are much less complex, and that many physically relevant states belong to such subspaces and can be more efficiently described. The second approach is to give up entirely on describing the complete state, focusing instead on direct measurements of its interesting properties. Beyond the expectation values of measurements of individual qubits, more complex quantities such as correlation functions and entanglement entropy between sub-systems can yield important, high-level information about a state. Both of these strategies have been successfully applied in theoretical and numerical studies of quantum many-body systems. However, their application in experiments is much less developed. My research interest is in developing experimental tools to characterize large quantum systems. In pursuit of this goal, I am building an experimental platform that seamlessly combines quantum simulation and quantum computing techniques, based on an array or neutral Yb atoms in optical tweezers interacting via Rydberg excitations. The advantage of combining these approaches is that ÒanalogÓ quantum simulation can be used to controllably and reproducibly generate non-trivial nay-body quantum states (with size and coherence beyond what can presently be achieved with universal quantum computers), while ÒdigitalÓ quantum logic operations can be used to process these states before measurement to expose information that would not otherwise be accessible. The results of this work will have an impact on both parent fields. In the context of quantum simulators, developing tools for characterizing large quantum states will be vital for exploring systems that are truly unknown, to uncover new physics. In quantum computing and communication, state and process characterization is crucial for understanding and eliminating sources of errors. Lastly, the pursuit of this project involves developing a new experimental platform, which may open a new route to scalable quantum computing.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810215
Entities
People
- Jeffrey Thompson
Organizations
- Army Contracting Command
- Princeton University
- United States Army