Controlling, detecting and entangling alkaline-earth Rydberg atoms in tweezer arrays

Patent metadata

Field	Value
Publication number	US-11631024-B2
Application number	US-202117172885-A
Country	US
Kind code	B2
Filing date	Feb 10, 2021
Priority date	Feb 10, 2020
Publication date	Apr 18, 2023
Grant date	Apr 18, 2023

Abstract

An apparatus useful for creating and measuring states of an entangled system, comprising a pair of interacting multi-level systems, each of systems comprising a state |g>; a state |r>, and state |r*>. One or more first electromagnetic fields excite a first transition between the ground state |g> and the state |r> to create an entangled system. One or more second electromagnetic fields are tuned between the state |r> and the intermediate state |r*> so that any population of the systems in |r*> are dark to a subsequent detection of a population in the systems in |g>, providing a means to distinguish the entangled system in the state |g> and the entangled system in the state |r>. In one or more examples, the systems comprise neutral Rydberg atoms.

First claim

What is claimed is:

1. An apparatus useful for creating and measuring states of an entangled system, comprising:
a pair of interacting multi-level systems, each of systems comprising:
a ground state |g>;
a state |r>, wherein the interacting is such that excitation to the state |r> in one of the systems prevents excitation to the state |r> in the other of the systems; and
an intermediate state |r*>, wherein a population of the systems in the intermediate state |r*> does not decay to the ground state |g>;

one or more sources of coherent electromagnetic radiation coupled to the systems and emitting:
one or more first electromagnetic fields tuned to excite a first transition between the ground state |g> and the state |r>, wherein the excitation of the first transition creates an entangled system comprising an entanglement of the pair of interacting multi-level systems; and
one or more second electromagnetic fields tuned between the state |r> and the intermediate state |r*> to excite a second transition to the intermediate state |r*> so that any population of the systems in intermediate state |r*> are dark to a subsequent detection of a population in the systems in the ground state |g>, providing a means to distinguish the entangled system in the ground state |g> and the entangled system in the state |r>;
a detection system performing the detection of whether there is the population of the entangled system in the ground state |g>.

2. The apparatus of claim 1 , wherein:
each of the systems include:
an auxiliary state |a>, such that the entangled system in state |g> does not decay to the auxiliary state |a> and a transition from the auxiliary state |a> to the state |r> is forbidden; and
a state |f> having an energy higher than the auxiliary state |a>, such that the intermediate state |r*> is not electromagnetically coupled to the state |f>;

the one or more sources of coherent electromagnetic radiation emit:

one or more third electromagnetic fields:
exciting a third transition from the ground state |g> to state |f>; or
exciting a fourth transition from the ground state |g> to the auxiliary state |a> and then a fifth transition from auxiliary state |a> to the state |f>; and
the detection system comprises a detector and the one or more sources emitting one or more fourth electromagnetic fields exciting a sixth transition from the auxiliary state |a> to the state |f>, such that the detector detecting spontaneous emission from the state |f> in response to excitation of the sixth transition indicates the population of the entangled system in the ground state |g>.

3. The apparatus of claim 1 , wherein the systems comprise Rydberg atoms, the state |r> is a Rydberg state, and the pair of Rydberg atoms are separated by a distance less than or equal to a Rydberg blockade radius so that the interacting comprises a Rydberg blockade.

4. The apparatus of claim 3 , wherein the auxiliary state |a> comprises a 1 S 0 state, the ground state |g> comprises a 3 P 0 state and the |r> state comprises a 3 S 1 state.

5. The apparatus of claim 3 , wherein the systems comprise alkaline earth atoms or alkaline earth-like atoms.

6. The apparatus of claim 5 , wherein the atoms comprise Strontium, Ytterbium, or an atom having two valence electrons including one electron that can be excited from a core and one electron that can be in the state |r>.

7. The apparatus of claim 3 , wherein:
the atoms each comprise a multi-electron atom;
the state |r> is defined as n G sn R 3 S 1 , where n R ≥30 is the principal quantum number of the |r> state, n G is the principal quantum number of the ground state |g>, s is the angular momentum quantum number, and S is a term symbol representing the total orbital angular momentum quantum number of the multi-electron atom;
the state |g> is defined as n G sn G p 3 P 0 , where p is the angular momentum quantum number, and P is the total orbital angular momentum quantum number for the multi-electron atom; and
the intermediate state |r*> is defined as n G sn R s 3 S 1 .

8. The apparatus of claim 3 , further comprising a trap comprising trapping potentials trapping an array of the multi-level systems, each of the trapping potentials trapping a single one of the atoms.

9. The apparatus of claim 8 , wherein the trap comprises optical tweezers.

10. The apparatus of claim 8 , further comprising a controller controlling the trapping potentials so that the detection mechanism measures whether there is the population of the entangled system in the ground state |g> while the systems are trapped in the trapping potentials.

11. A quantum computer, a sensor, a clock, or a quantum simulator comprising the apparatus of claim 1 .

12. The apparatus of claim 1 , wherein the detection mechanism is used to measure a state of a qubit comprising the ground state |g> and the state |r>.

13. The apparatus of claim 1 , wherein the interacting comprises an interaction, preventing excitation to the state |r> in one of the systems when there is excitation to the state |r> in the other of the systems, comprises a dipole interaction, an electrostatic interaction, or an electromagnetic interaction.

14. The apparatus of claim 1 , wherein the intermediate state |r*> is a short-lived compared to timescale for a transition from the state |r> to the state |g>.

15. The apparatus of claim 1 , wherein the intermediate state |r*> transitions to a dark state of the systems faster than a transition from the state |r*> to the state |r>.

16. The apparatus of claim 1 , wherein the systems comprise atoms, quantum dots, defects in solid state, a superconductor, or a charge qubit circuit.

17. A method for creating and measuring states of an entangled system, comprising:
trapping a pair of interacting multi-level systems, each of systems comprising:
a ground state |g>;
a state |r>, wherein the interacting is such that excitation to the state |r> in one of the systems prevents excitation to the state |r> in the other of the systems; and
an intermediate state |r*>;

emitting:
one or more first electromagnetic fields tuned to excite a first transition between the ground state |g> and the state |r>, wherein the excitation of the first transition creates an entangled system comprising an entanglement of the pair of interacting multi-level systems; and
one or more second electromagnetic fields tuned between the state |r> and the intermediate state |r*> to excite a second transition to the intermediate state |r*> so that any population of the systems in intermediate state |r*> are dark to a subsequent detection of a population in the systems in |g=, providing a means to distinguish the entangled system in the state |g> and the entangled system in the state |r>; and

performing the detection of whether there is the population of the entangled system in the ground state |g>.

18. The method of claim 17 , wherein:
each of the systems include:
an auxiliary state |a>, such that the entangled system in state |g> does not decay to the auxiliary state |a> and a transition from the auxiliary state |a> to the state |r> is forbidden; and
a state |f> having an energy higher than state |a>, such that the intermediate state |r*> is not electromagnetically coupled to the state |f>;

the emitting further comprises one or more sources of coherent electromagnetic radiation emitting:

one or more third electromagnetic fields:
exciting a third transition from the ground state |g> to state |f>; or
exciting a fourth transition from the ground state |g> to the auxiliary state |a> a

Assignees

• California Inst Of Techn

Inventors

• Endres Manuel
• Cooper-Roy Alexandre
• Covey Jacob P
• Madjarov Ivaylo S
• Shaw Adam L
• Schkolnik Vladimir
• Williams Jason R
• Choi Joonhee

Classifications

• G21K1/20

  for confining charged particles or handling confined charged particles, e.g. ion traps · CPC title

• G06N10/00 Primary

  Quantum computing, i.e. information processing based on quantum-mechanical phenomena · CPC title

• G06N10/40 Primary

  Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• H04B10/70

  Photonic quantum communication · CPC title