Search

US-12626833-B2 - Topological qubits in a quantum spin liquid

US12626833B2US 12626833 B2US12626833 B2US 12626833B2US-12626833-B2

Abstract

Topological qubits are provided in a quantum spin liquid. In various embodiments, a device is provided comprising a two-dimensional array of particles, each particle disposed at a vertex of a ruby lattice having a parameter ρ greater than 1 2 ; each particle having a first state and an excited state; each particle that belongs to at least three unit cells of the ruby lattice having a blockade radius, when in the excited state, sufficient to blockade each of at least six nearest neighboring particles in the ruby lattice from transitioning from its first state to its excited state, and wherein the array has at least one outer edge configured to be in a first boundary condition.

Inventors

  • Mikhail D. Lukin
  • Ahmed Omran
  • Dolev Bluvstein
  • Sepehr Ebadi
  • Vladan Vuletic
  • Markus Greiner
  • Ruben Verresen
  • Ashvin Vishwanath
  • Alexander Keesling Contreras
  • Harry Jay Levine
  • Giulia Semeghini
  • Tout Taotao Wang

Assignees

  • PRESIDENT AND FELLOWS OF HARVARD COLLEGE
  • MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Dates

Publication Date
20260512
Application Date
20230519

Claims (20)

  1. 1 . A device, comprising: a two-dimensional array of particles, each particle disposed at a vertex of a ruby lattice having a parameter ρ greater than 1 2 ; each particle having a first state and an excited state; each particle that belongs to at least three unit cells of the ruby lattice having a blockade radius, when in the excited state, sufficient to form a blockade of each of at least six nearest neighboring particles in the ruby lattice from transitioning from its first state to its excited state, and wherein the two-dimensional array has at least one outer edge configured to be in a first boundary condition.
  2. 2 . The device of claim 1 , wherein each particle is an atom, an ion, or a molecule.
  3. 3 . The device of claim 1 , wherein the blockade is a dipole blockade.
  4. 4 . The device of claim 1 , wherein the blockade is a Rydberg blockade.
  5. 5 . The device of claim 1 wherein each particle is an atom, the first state is ground state, and the blockade is a Rydberg blockade.
  6. 6 . The device of claim 1 , wherein the two-dimensional array comprises at least a first outer edge and a third outer edge, each being in the first boundary condition, and at least a second outer edge and a fourth outer edge, each being in a second boundary condition, different from the first boundary condition.
  7. 7 . The device of claim 1 , wherein the two-dimensional array has a plurality of outer edges, each outer edge being either in the first boundary condition or a second boundary condition, each outer edge being in a different boundary condition than any adjacent outer edge.
  8. 8 . The device of claim 6 , wherein the outer edges configured to be in the first boundary condition are e-condensed, and the outer edges configured to be in the second boundary condition are m-condensed.
  9. 9 . The device of claim 7 , wherein the two-dimensional array comprises at least one interior edge.
  10. 10 . The device of claim 9 , wherein each vertex enclosed by the at least one interior edge is not particle-occupied.
  11. 11 . The device of claim 10 , wherein the at least one interior edge is at a same boundary condition as at least one outer edge of the plurality of outer edges.
  12. 12 . The device of claim 9 , wherein the at least one interior edge encloses at least four vertices.
  13. 13 . The device of claim 9 , wherein the at least one interior edge encloses particle-occupied vertices.
  14. 14 . The device of claim 13 , wherein the at least one interior edge is in the first boundary condition, different from at least one outer edge of the plurality of outer edges.
  15. 15 . The device of claim 9 , wherein the two-dimensional array has a plurality of interior edges, each interior edge enclosing a corresponding plurality of vertices, each of which is not particle-occupied.
  16. 16 . The device of claim 9 , wherein the two-dimensional array has a plurality of interior edges, each interior edge enclosing a corresponding plurality of vertices, wherein at least one enclosed vertex is particle-occupied.
  17. 17 . The device of claim 16 , wherein an interior edge enclosing the at least one enclosed vertex that is particle-occupied is at a boundary condition different from at least one outer edge of the plurality of outer edges.
  18. 18 . The device of claim 17 , wherein edges configured to be at different boundary conditions are selected from e-condensed or m-condensed edges.
  19. 19 . The device of claim 1 , wherein the two-dimensional array comprises at least 96 particles.
  20. 20 . The device of claim 1 , wherein the two-dimensional array comprises at least 200 particles.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/US2021/060138, filed Nov. 19, 2021, which claims the benefit of U.S. Provisional Application No. 63/116,321, filed Nov. 20, 2020, and of U.S. Provisional Application No. 63/166,165, filed Mar. 25, 2021, each of which is hereby incorporated by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under DE-SC0021013 awarded by U.S. Department of Energy (DOE) and under 2012023 and 1734011 awarded by National Science Foundation (NSF) and under W911NF-20-1-0082 awarded by U.S. Army Research Office (ARO). The government has certain rights in the invention. BACKGROUND The linchpin of fault tolerant quantum computing is a quantum code that protects quantum information from decoherence and errors by the environment. By far the most studied error correcting code is the so called surface code. However, practical implementations of the surface code have lagged behind theory. Embodiments of the present disclosure relate to the creation of a quantum spin liquid and the implementation of qubits and qubit operations therein. BRIEF SUMMARY In a 1st example embodiment, the presence invention is a device. In the 1st aspect, the device comprises a two-dimensional array of particles, each particle disposed at a vertex of a ruby lattice having a parameter ρ greater than 12; each particle having a first state and an excited state; each particle that belongs to at least three unit cells of the ruby lattice having a blockade radius, when in the excited state, sufficient to blockade each of at least six nearest neighboring particles in the ruby lattice from transitioning from its first state to its excited state, and wherein the array has at least one outer edge configured to be in a first boundary condition. In a 2nd example embodiment, the present invention is a system. The system comprises a confinement system for arranging particles in a two-dimensional array, and an excitation source for exciting at least some of the particles from the first state to the excited state. The confinement system comprises a laser source arranged to create a plurality of confinement regions; a source of an atom cloud, the atom cloud capable of being positioned to at least partially overlap with the plurality of confinement regions. In a 1st aspect of the 2nd example embodiment, in the two-dimensional array, each particle is disposed at a vertex of a ruby lattice; each particle has a first state and an excited state; each particle that belongs to at least three unit cells of the ruby lattice has a blockade radius, when in the excited state, sufficient to blockade each of at least six nearest neighboring particles in the ruby lattice from transitioning from its first state to its excited state, and wherein the array has at least one outer edge configured to be at a first boundary condition. In a 3rd example embodiment, the present invention is a method of making a 2 Quantum Spin Liquid (2 QSL). In a 1st aspect, the method comprises arranging a two-dimensional array of particles, wherein each particle is disposed at a vertex of a ruby lattice having a parameter ρ greater than 12; each particle has a first state and an excited state; and the array has at least one outer edge. The method further comprises exciting about 25% of the particles into the excited state, thereby causing each particle in the excited state that belongs to at least three unit cells of the ruby lattice to have a blockade radius sufficient to blockade at least six nearest neighboring particles in the ruby lattice; and, optionally, imposing a first boundary condition on the at least one outer edge. In a 4th example embodiment, the present invention is a method of encoding a topological qubit in a 2 Quantum Spin Liquid (2 QSL). The method comprises preparing a 2 QSL according to the method defined in the 3rd example embodiment and any of its aspects, as described above. In a 1st aspect of the 4th example embodiment, the array comprises at least a first outer edge, a second outer edge, a third outer edge, and a fourth outer edge; and imposing a first boundary condition on the first and third outer edges and imposing a second boundary condition on the second and fourth outer edges. In a 5th example embodiment, the present invention is a method of encoding a topological qubit in a 2 Quantum Spin Liquid (2 QSL). The method comprises preparing a 2 QSL according to the method defined in the 3rd example embodiment. In a 1st aspect of the 5th example embodiment, the array comprises at least one interior edge. In a 6th example embodiment, the present invention is a method of reading a state of a topological qubit encoded in a 2 Quantum Spin Liquid (2 QSL). In a 1st aspect of the 6th example embodiment, the method comprises receiving an indication of a state of each particle of a two-dimensional array