US-12618884-B2 - Ultrafast detector of rydberg atoms

US12618884B2US 12618884 B2US12618884 B2US 12618884B2US-12618884-B2

Abstract

A device, comprising at least one monochromatic light source configured to generate a first optical trap; an ensemble of particles disposed in the first optical trap, each particle of the ensemble of particles being excitable to a first Rydberg state and a second Rydberg state, the second Rydberg state having a blockade radius, each particle of the ensemble of particles being within the blockade radius of each other and within the blockade radius of an atomic qubit, the atomic qubit being a particle that is excitable to the second Rydberg state, the ensemble of particles having a first transmissivity at a first wavelength when neither any particle of the ensemble of particles nor the atomic qubit is in the second Rydberg state, the ensemble of particles having a second transmissivity at the first wavelength when the atomic qubit is in the second Rydberg state, the second transmissivity being lower than the first transmissivity; and a second monochromatic light source configured to drive each particle of the ensemble of particles into the first Rydberg state; a probe light source configured to direct a probe beam having the first wavelength to the ensemble of particles; and a photosensor configured to determine the state of the atomic qubit.

Inventors

Wenchao XU
Vladan Vuletic
Sergio Hiram Cantu
Valentin Kluesener
Aditya Vignesh Venkatramani
Mikhail D. Lukin
Tamara Sumarac

Assignees

PRESIDENT AND FELLOWS OF HARVARD COLLEGE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Dates

Publication Date: 20260505
Application Date: 20230811

Claims (20)

1 . A method of determining a state of an atomic qubit, the method comprising: arranging an ensemble of particles, wherein particles of the ensemble of particles are excitable to a first Rydberg state having a blockade radius; driving a particle of the ensemble of particles from a ground state into the Rydberg state; moving an atomic qubit within the blockade radius of a particle of the ensemble of particles, wherein the atomic qubit is a particle that is excitable to the Rydberg state; directing a probe beam having a first wavelength to the ensemble of particles, wherein: the ensemble of particles has a first transmissivity at a first wavelength when neither any particle of the ensemble of particles nor the atomic qubit is in the Rydberg state, and the ensemble of particles has a second transmissivity at the first wavelength when the atomic qubit is in the Rydberg state, the second transmissivity being lower than the first transmissivity; and determining the state of the atomic qubit.
2 . The method of claim 1 , wherein determining the state of the atomic qubit comprises measuring a transmission of the probe beam by the ensemble of particles.
3 . The method of claim 1 , wherein determining the state of the atomic qubit comprises measuring fluorescence of the ensemble of particles at the first wavelength.
4 . The method of claim 1 , further comprising: performing a computation using the atomic qubit prior to driving any one particle of the ensemble of particles into the Rydberg state.
5 . The method of claim 1 , wherein: moving the atomic qubit comprises moving the atomic qubit using an acousto-optic deflector.
6 . The method of claim 1 , wherein the particle is driven to an intermediate Rydberg state and then to the Rydberg state using a three-photon driving process.
7 . The method of claim 6 , wherein the three-photon driving process comprises: performing a first driving step wherein the particle is driven from the ground state into an excited state using a first laser, performing a second driving step wherein the particle is driven from the excited state into the intermediate Rydberg state using a second laser; and performing a third driving step wherein the particle from the intermediate Rydberg state is driven into the Rydberg state using a microwave field.
8 . The method of claim 7 , wherein the three-photon driving process further comprises: detuning the first laser by Δ e /(2π)=δ r /(2π) from its respective transition, and detuning the microwave field by Δ e /(2π)=δ r /(2π) from its respective transition.
9 . A quantum computer, comprising: an acousto-optical deflector configured to, during operation of the quantum computer: generate an ensemble of optical traps for trapping atomic qubits, the ensemble of traps being arranged to form: a detection region; and a computational region; and move an atomic qubit from the computational region to the detection region; a first laser and a second laser configured to perform two-photon entanglement gates between atomic qubits, wherein the second laser is further configured to illuminate the ensemble of optical traps; and a photosensor configured to determine a state of the atomic qubit.
10 . The quantum computer of claim 9 , wherein the acousto-optical deflector is configured to arrange an array of trapped ensembles of atoms in the detection region, wherein: atoms of the ensemble of atoms are excitable to a first Rydberg state and a second Rydberg state, the second Rydberg state having a second blockade radius, and atoms of the ensemble of atoms are disposed within the second blockade radius of another atom of the ensemble of atoms.
11 . The quantum computer of claim 10 , wherein the acousto-optical deflector is configured to arrange an array of trapped atomic qubits in the computational region, wherein the atomic qubits are atoms that are excitable to the second Rydberg state.
12 . The quantum computer of claim 9 , wherein the acousto-optical deflector is configured to generate multiple diffraction orders using multiple trap positions.
13 . The quantum computer of claim 12 , wherein the acousto-optical deflector is configured to control the multiple trap positions in real time.
14 . The quantum computer of claim 9 , wherein the quantum computer further comprises at least one filter configured to pulse shape an intensity, a frequency, and/or a phase of the first laser and/or the second laser.
15 . The quantum computer of claim 14 , wherein the first laser comprises a Rydberg laser.
16 . The quantum computer of claim 14 , wherein the second laser comprises a probing laser.
17 . The quantum computer of claim 14 , wherein the photosensor is configured to determine the state of the atomic qubit by measuring a transmitted light of the second laser through the ensemble of optical traps.
18 . The quantum computer of claim 9 , wherein the quantum computer further comprises a third laser and a fourth laser configured to form a crossed optical dipole trap.
19 . The quantum computer of claim 18 , wherein the third laser and the fourth laser are configured to generate orthogonal far-detuned laser beams.
20 . A method of reading out states of atomic qubits, the method comprising: generating an ensemble of optical traps, the ensemble of optical traps comprising: a detection region; and a computation region; trapping an ensemble of atoms in the detection region, wherein: atoms of the ensemble of atoms are excitable to a Rydberg state having a blockade radius, and atoms of the ensemble of atoms are disposed within the blockade radius of another atom of the ensemble of atoms, trapping atomic qubits in the computation region, an atomic qubit being an atom that is excitable to the Rydberg state; entangling the atomic qubits into a collective state in the computation region; moving an atomic qubit from the computation region to the detection region; determining the collective state of the atomic qubits; and moving the atomic qubit from the detection region to the computation region.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of Internation Application No. PCT/US2022/016173, filed Feb. 11, 2022, which claims the benefit of U.S. Provisional Application No. 63/148,995, filed Feb. 12, 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 1125846 and 1506284 awarded by National Science Foundation (NSF) and under W911NF-20-1-0021 and W911NF-15-2-0067 awarded by U.S. Army Research Office (ARO) and under D18AC00037 awarded by U.S. Department of Defense/Defense Advanced Research Projects Agency (DOD/DARPA). The government has certain rights in the invention. BACKGROUND Embodiments of the present disclosure relate to Rydberg atom based quantum computation, and more specifically, to ultrafast detection of Rydberg atoms. BRIEF SUMMARY In an example embodiment, the present invention is a device, comprising: at least one monochromatic light source configured to generate a first optical trap; an ensemble of particles disposed in the first optical trap, each particle of the ensemble of particles being excitable to a first Rydberg state and a second Rydberg state, the second Rydberg state having a blockade radius, each particle of the ensemble of particles being within the blockade radius of each other and within the blockade radius of an atomic qubit, the atomic qubit being a particle that is excitable to the second Rydberg state, the ensemble of particles having a first transmissivity at a first wavelength when neither any particle of the ensemble of particles nor the atomic qubit is in the second Rydberg state, the ensemble of particles having a second transmissivity at the first wavelength when the atomic qubit is in the second Rydberg state, the second transmissivity being lower than the first transmissivity; and a second monochromatic light source configured to drive each particle of the ensemble of particles into the first Rydberg state; a probe light source configured to direct a probe beam having the first wavelength to the ensemble of particles; and a photosensor configured to determine the state of the atomic qubit. In another example embodiment, the present invention is a device, comprising: at least a first monochromatic light source configured to generate a first array of optical traps, each optical trap of the first array of optical traps having an ensemble of particles disposed therein; at least a second monochromatic light source configured to generate a second array of optical traps, wherein: each particle of each of the ensembles of particles being excitable to a first Rydberg state and a second Rydberg state, the second Rydberg state having a blockade radius, each particle of each of the ensembles of particles being within the blockade radius of the second Rydberg state of each particle in its ensemble, and of at least one optical trap of the second array of optical traps, the at least one optical trap of the second array having an atomic qubit disposed therein, the atomic qubit being a particle that is excitable to the second Rydberg state, each ensemble of particles having a first transmissivity at a first wavelength when none of its particles is in the second Rydberg state, each ensemble of particles having a second transmissivity at the first wavelength when one particle in the at least one optical trap of the second array of optical traps is in the second Rydberg state, the second transmissivity being lower than the first transmissivity, each particle of each ensemble of particles being outside the blockade radius of the second Rydberg state of each particle of any other ensemble of particles; at least a third monochromatic light source configured to drive each particle of each ensemble of particles into the first Rydberg state; a probe light source configured to direct a probe beam having the first wavelength to the ensembles of particles; and a photosensor configured to determine a quantum mechanical state of at least one particles in the ensembles of particles. In yet another example embodiment, the present invention is a method of determining a state of an atomic qubit. The method comprises: disposing an ensemble of particles proximate to an atomic qubit, wherein: each particle of the ensemble of particles being excitable to a first Rydberg state and a second Rydberg state, the second Rydberg state having a second blockade radius, the atomic qubit being a particle that is excitable to the second Rydberg state, each particle of the ensemble of particles being within the second Rydberg state blockade radius of each other and within the second Rydberg state blockade radius of the atomic qubit, the ensemble of particles having a first transmissivity at a first wavelength when neither any particle of the ensemble of particles nor the atomic qubit is in the second Rydberg state, the ensemble of particles having a