# US 10,375,813 B2 · On-chip trapped ultracold atom sensor allowing rotational velocity to be measured

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- Number: US 10,375,813 B2
- Document ID: US10375813B2
- Status: Granted
- Kind: B2
- Application number: 15/778,605
- Filed: 2016-11-24
- Published: 2018-12-06
- Granted: 2019-08-06
- Earliest claimed: 2015-11-27
- Assignees: Thales
- Applicants: Thales
- Inventors: Matthieu Dupont-Nivet; Sylvain Schwartz
- Web page: https://patentgrep.com/patent/US10375813B2

## CPC

- H05H 3/00: Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
- G01C 19/64: Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## Abstract

Ultra-cold atom sensor for measuring a rotational velocity along a measurement axis comprises: means designed to generate a first and a second ultra-cold atom trap, one trap making it possible to immobilize a cloud of ultra-cold atoms in an internal state different from the other trap, at a predetermined distance from the measurement plane, the means comprising, at least one first and one second waveguide that are designed to propagate microwaves with angular frequencies ωa and ωb, the waveguides being non-secant and positioned symmetrically about an axis called the axis of symmetry, conductive wires integrated into the chip and designed to be flowed through by DC currents, the means being configured to modify the energy of the ultra-cold atoms in such a way as to create a potential minimum for the ultra-cold atoms in the internal state |a> and a potential minimum for the ultra-cold atoms in the internal state |b>, thus forming the first and second ultra-cold atom traps, and to move the traps along a closed path, traveled in one direction by the ultra-cold atoms of the first trap and in the opposite direction by the ultra-cold atoms of the second trap.

## Claims

### Claim 1

An ultra-cold atom sensor for measuring a rotational velocity along a measurement axis, said sensor comprising:
an electronic chip positioned in a vacuum chamber and including a measurement plane normal to said measurement axis;
an atom source arranged so as to generate a cloud of ultra-cold atoms close to said measurement plane;
an electromagnetic wave emitter designed to initialize the internal states of said ultra-cold atoms at a superposition of internal states |a> and |b>;
means designed to generate a first and a second ultra-cold atom trap, one trap making it possible to immobilize a cloud of ultra-cold atoms in an internal state different from the other trap, at a predetermined distance from said measurement plane, said means comprising:
at least one first and one second waveguide that are designed to propagate microwaves with angular frequencies ωa and ωb, said waveguides being non-secant and positioned symmetrically about an axis called the axis of symmetry Sy,
conductive wires integrated into said chip and designed to be flowed through by DC currents, distributed into a first set comprising at least one conductive wire, and a second set comprising a plurality of n conductive wires that are parallel with one another and not parallel with the said axis of symmetry Sy,
said sets being arranged such that the at least one conductive wire of the first set is not parallel with the conductive wires of the second set, defining n points of intersection between any one conductive wire of the first set and one or more conductive wires of the second set, said n points of intersection between the any one conductive wire of the first set and the one or more conductive wires of the second set being located on the axis of symmetry Sy,
a homogeneous magnetic field generator,
an optical intensity detection system designed to measure at least one population of said ultra-cold atoms in one said internal state;
at least one processor, at least one DC current or voltage generator designed to control electric currents in said conductive wires, and at least one microwave current or voltage generator connected to said waveguides,
said means being configured to modify the energy of said ultra-cold atoms in such a way as to create a potential minimum for the ultra-cold atoms in the internal state |a> and a potential minimum for the ultra-cold atoms in the internal state |b>, thus forming said first and second ultra-cold atom traps, and to move said traps along a closed path, traveled in one direction by the ultra-cold atoms of the first trap and in the opposite direction by the ultra-cold atoms of the second trap.

### Claim 2 (depends on 1)

The sensor as claimed in claim 1, wherein the temperature of the ultra-cold atoms is greater than 20 nanokelvin and less than 400 nanokelvin.

### Claim 3 (depends on 1)

The sensor as claimed in claim 1, wherein the direction of said homogeneous magnetic field is parallel to said measurement plane.

### Claim 4 (depends on 1)

The sensor as claimed in claim 1, wherein the two waveguides are parallel with one another.

### Claim 5 (depends on 1)

The sensor as claimed in claim 1, wherein the first set consists of a single conductive wire coincident with the axis of symmetry, and wherein each of the said n points of intersection is between the single conductive wire of the first set and one of n conductive wires of the second set.

### Claim 6 (depends on 5)

The sensor as claimed in claim 5, wherein the conductive wires of the second set are not perpendicular to the single conductive wire of the first set.

### Claim 7 (depends on 1)

The sensor as claimed in claim 1, wherein the first set comprises a plurality of n conductive wires that are parallel with one another, wherein each of said n points of intersection is between one of the n conductive wires of the first set and one of n conductive wires of the second set.

### Claim 8 (depends on 7)

The sensor as claimed in claim 7, wherein an angle between the conductive wires of the first set and the conductive wires of the second set is between 30° and 60°.

### Claim 9 (depends on 7)

The sensor as claimed in claim 7, wherein the first set furthermore comprises a conductive wire coincident with the axis of symmetry.

### Claim 10 (depends on 1)

The sensor as claimed in claim 1, wherein the two waveguides and the conductive wires that are secant to said waveguides are respectively positioned on a first level and a second level that are separated by an insulator.

### Claim 11 (depends on 10)

The sensor as claimed in claim 10, wherein all of the conductive wires of the first and of the second set are positioned on the second level.

### Claim 12 (depends on 10)

The sensor as claimed in claim 10, further comprising a third set comprising a first and a second conductive wire that are positioned symmetrically about the axis of symmetry and in parallel with the first and with the second waveguides, respectively, and positioned on the first level.

### Claim 13 (depends on 1)

The sensor as claimed in claim 1, wherein each said waveguide is chosen from among a microstrip line, a coplanar line and preferably a coplanar line including three conductive wires that are parallel with one another and electrically insulated from the conductive wires of the first and of the second set, and of the third set where applicable.

### Claim 14 (depends on 1)

The sensor as claimed in claim 1, wherein said optical intensity detection system is designed to measure, at a single point on said path, at least one population of said ultra-cold atoms in one said internal state.

### Claim 15 (depends on 14)

The sensor as claimed in claim 14, wherein said optical intensity detection system includes at least one laser at least one wavelength of which corresponds to an absorption peak of the light intensity by said ultra-cold atoms in one said internal state.

### Claim 16 (depends on 1)

The sensor as claimed in claim 1, wherein the difference between the length of said closed path taken by two said traps is less than the de Broglie length of said ultra-cold atoms.