Granted Patent B2

US 12,618,884 · App. 18/233,088 · Granted May 5, 2026

Inventors: Wenchao Xu (Cambridge, MA); Vladan Vuletic (Cambridge, MA); Sergio Hiram Cantu (Cambridge, MA); Valentin Kluesener (Erlangen, DE); Aditya Vignesh Venkatramani (Boston, MA); Mikhail D. Lukin (Cambridge, MA); Tamara Sumarac (Cambridge, MA)

Assignees: President and Fellows of Harvard College; Massachusetts Institute of Technology

G01R29/0885G01R29/0807G01R29/0871G06N10/40

Abstract

Claims (67)

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.

21 . The method of claim 20 , wherein generating an ensemble of optical traps comprises loading atomic qubits and the ensemble of atoms into crossed optical dipole traps.

22 . The method of claim 20 , wherein entangling the atomic qubits in a collective state comprises using a first laser and a second laser to perform two-photon entanglement gates.

23 . The method of claim 22 , wherein performing two-photon entanglement gates on the atomic qubits comprises pulse shaping an intensity, a frequency, and/or a phase of the first laser and/or the second laser.

24 . The method of claim 22 , wherein determining the collective state of the atomic qubits comprises:

illuminating the ensemble of atoms with light using the second laser; and

measuring light transmitted through the ensemble of atoms using a photodetector.

25 . The method of claim 24 , wherein determining the collective state of the atomic qubits of the second laser occurs under conditions of conditions of electromagnetically induced transparency (EIT).

26 . The method of claim 20 , wherein moving atomic qubits comprises:

generating moving traps with an acousto-optic deflector;

loading atomic qubits into the moving traps; and

moving the moving traps using the acousto-optic deflector.

27 . The method of claim 26 , wherein moving the atomic qubits further comprises moving the atomic qubits within the blockade radius of an atom of the ensemble of atoms.

28 . The method of claim 20 , wherein determining the collective state of the atomic qubits comprises measuring a fluorescence of the ensemble of atoms.

Assignments (2)

Continuity (3)

References Cited (211)