# US 2013/0152680 A1 · Atom-based accelerometer

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- Number: US 2013/0152680 A1
- Document ID: US20130152680A1
- Status: Published application
- Kind: A1
- Application number: 13/327,294
- Filed: 2011-12-15
- Published: 2013-06-20
- Earliest claimed: 2011-12-15
- Assignees: Honeywell International Inc.
- Inventors: Charles Sackett; Mary Salit; Kenneth Salit; Robert Compton
- Web page: https://patentgrep.com/patent/US20130152680A1

## CPC

- G01P 15/093: by photoelectric pick-up
- G01P 15/08: with conversion into electric or magnetic values
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})

## Abstract

An atom-based accelerometer for measuring acceleration or gravity with an interaction region less than a millimeter in size. An exemplary device includes a magnetic double-well trap produced on a chip. Creation and dissolution of the double-well trap is provided by interaction between an ac magnetic field and a radio frequency (rf) magnetic field produced by traces on the chip.

## Claims

### Claim 1

A method comprising:
at an atom accelerometer in a vacuum,
generating, capturing and cooling a cloud of ultracold atoms;
generating an alternating current (AC) magnetic field with a trapping region that represents a local field minimum in three dimensions;
separating the atom cloud into two spatially displaced packets of atoms using radio frequency (rf) magnetic fields,
allowing the two packets to be recombined into a single atom cloud;
at a sensor measuring a phase of recombined single atom cloud after recombination; and
at a processor generating an acceleration value based on the measured phase.

### Claim 2 (depends on 1)

The method of claim 1, wherein measuring comprises optically measuring.

### Claim 3 (depends on 2)

The method of claim 2, further comprising electrically monitoring and controlling the trapping and splitting fields to optimize that optical measuring.

### Claim 4 (depends on 1)

The method of claim 1, wherein generating an acceleration value is further based on an estimated phase value.

### Claim 5

An accelerometer device comprising:
a substrate located at least partially within a vacuum, the substrate comprising:
an atom sources configured to generate and cool a cloud of atoms;
at least one first trace configured to generate an alternating current (AC) magnetic field thereby trapping the cloud of atoms in a trapping region;
at least one second trace configured to generate a radio frequency (rf) magnetic field, thereby separating the atom cloud into two spatially displaced packets of atoms;
a sensor configured to measure a phase of a single atom cloud after recombination occurs after atom cloud separation; and
a processor configured to generate an acceleration value based on the measured phase.

### Claim 6 (depends on 5)

The device of claim 5, wherein the sensor comprises an optical sensor.

### Claim 7

A method comprising:
at an atom accelerometer in a vacuum,
generating, capturing and cooling a cloud of ultracold atoms;
generating an array of magnetic traps using alternating current (AC) magnetic fields with multiple trapping regions that represents multiple local field minima in three dimensions;
separating the atom cloud into two spatially displaced packets of atoms using radio frequency (rf) magnetic fields, wherein the displacement is into traps with each trap displacing the packets by a different amount;
allowing the two packets in each trap to be recombined into a single atom cloud;
at a sensor measuring a phase of recombined single atom cloud after recombination; and
at a processor generating an acceleration value based on the measured phase inferred from the readout of the trap with the greatest separation distance, with any ambiguity in this phase resolved by the readout of the other traps.