Large-scale entanglement through mid-circuit measurements and feed-forward 23-000003449
Abstract
Approved for Public Release.-Large-scale entanglement through mid-circuit measurements and feed-forward -Hannes Bernien # University of Chicago-Project summary/abstract--We propose a research program that will develop and demonstrate efficient, scalable state preparation protocols of highly entangled states in a quantum processor. Entanglement is the essential resource for applications that leverage quantum effects for enhanced functionalities and advantage over classical technologies. For instance, highly entangled GHZ states would enable us to overcome sensitivity limits of classical sensors and large-scale cluster states would enable an alternative paradigm of quantum computing to the more traditional #gate-based# approach, which is called measurement-based quantum computing. However, generating large-scale entanglement is an enormous challenge not only because of stringent requirements on operation fidelities and coherence times, but also because of the unfavorable scaling when attempting to create larger and larger entangled states. In general, using only unitary evolution, such as gates on a quantum processor, it is impossible to prepare entangled states in a time that is independent of system size. This makes scaling to large states unfeasible. Remarkably, using measurements and feed-forward operations to augment unitary evolution can overcome this challenge and lead to preparation protocols that create large-scale entangled states in constant time, independent of the system size. In our proposed research program, we will use a dual-species atom array as a quantum processor. Supported by grant N00014-20-1-2510 by the ONR, we have recently demonstrated the advantage of such an architecture and assembled dual-species atom arrays that consist of individually trapped rubidium and cesium atoms with up to 512 trapping sites. The fact that the two species have very different qubit frequencies and optical frequencies, enables us to independently control each atomic qubit without any crosstalk. Furthermore, we can measure the qubit states of one atomic species, without decohering the quantum state on the array of the other species. We used such mid- circuit readout to implement a qubit error mitigation protocol, in which one atomic qubit type monitors background noise in real-time and enables feed-forward operations that correct for the noise on the other atomic qubit type. Here, we will leverage the dual-species architecture and introduce interactions between the two species by exciting atoms to highly excited Rydberg states. We will demonstrate that we can perform high-fidelity entangling operations on one atomic species by mediating these gates with the other species. This will result in a large-scale cluster state. Furthermore, adding mid-circuit measurements to this approach results in a protocol to generate large GHZ states. Finally, we will investigate the efficient execution of fan-out gates in this architecture which could lead to constant depth realizations of important quantum algorithms such as the quantum Fourier transform (QFT).The research program in this proposal is directly relevant to the research interests of to the ONR in general, and in particular to the goals of the technology areas Quantum Information Science and Atomic, Molecular and Quantum Physics of ONR. The proposed research will lead to the efficient generation of highly entangled state in constant depth circuits. Such states are the essential resource for a vast majority of quantum technologies.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 29, 2023
- Source ID
- N000142312540
Entities
People
- Hannes Bernien
Organizations
- Office of Naval Research
- United States Navy
- University of Chicago