# US 2018/0020534 A1 · Measurement by atomic interferometry with multiple species of atoms > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0020534 A1 - Document ID: US20180020534A1 - Status: Published application - Kind: A1 - Application number: 15/549,697 - Filed: 2016-02-10 - Published: 2018-01-18 - Earliest claimed: 2015-02-16 - Assignees: ONERA (Office National d'Etudes et de Recherches Aerospatiales) - Applicants: Onera (Office National D'Etudes Et De Recherches Aerospatiales - Inventors: Nassim ZAHZAM; Yannick BIDEL; Alexandre BRESSON; Alexis BONNIN - Web page: https://patentgrep.com/patent/US20180020534A1 ## CPC - H05H 3/02: Molecular or atomic-beam generation, e.g. resonant beam generation - G01C 19/58: Turn-sensitive devices without moving masses - G01J 9/02: by interferometric methods (using interferometers for measuring optically the linear dimensions of objects G01B9/02) - G01P 15/08: with conversion into electric or magnetic values - G01P 15/093: by photoelectric pick-up - G01V 7/00: Measuring gravitational fields or waves; Gravimetric prospecting or detecting - 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) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - 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}) - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract Disclosed is a method for measuring an external parameter by atomic interferometry, using two sets of atoms that belong to different species. Two measurements are taken simultaneously at the same location, but independently from one another, in order to obtain two measurement results. One of these measurement results removes an indeterminacy among several possible values of the external parameter, by taking into account only the other measurement result. A method of this kind can be used to measure a coordinate of a gravitational field or a coordinate of an acceleration of the atoms. ## Claims ### Claim 1 Method of measurement by atomic interferometry, in which each session of measurements is executed with at least two sets of atoms (11, 12) each subjected to conditions of formation of an atomic interference, the atoms of each set of atoms (11, 12) being of a species dedicated to said set of atoms and different from the species of atoms of each other set of atoms, method in which, for each session of measurements, said conditions are produced for each set of atoms (11, 12) throughout a volume that is associated with said set of atoms and that contains at least one point in common with the volume associated with each other set of atoms, and are produced between a start time point and an end time point respectively before and after an intermediate time point that is common to all the sets of atoms, and in which a measurement result (P11, P12) is obtained in each session of measurements independently for each set of atoms (11, 12), each measurement result varying according to a first function of a phase shift that appeared for the set of atoms during the formation of the atomic interference, and said phase shift itself being a second function of an external parameter (a) a value of which is sought, said first function being alternately increasing and decreasing for at least a first (11) of the sets of atoms so that a measurement result (P11) that is obtained for said first set of atoms corresponds to several possible values of the external parameter (a) within a non-zero exploration interval, and said second function having, for at least one other (12) of the sets of atoms different from said first set of atoms (11), a derivative with respect to the value of the external parameter (a), that depends on at least one factor selected from a base time (T) for a sequence of interactions between the atoms and photons, and a number of photons involved in a multiphoton interaction, said sequence of interactions or said multiphoton interaction being implemented in order to form the atomic interference of said other set of atoms, wherein a value of the factor is selected in order to carry out a session of measurements, so that the measurement result (P12) that is obtained for said other set of atoms (12) corresponds to a single value of the external parameter (a) within the exploration interval, so that an indetermination between several values of the external parameter (a) that exists from the measurement result (P11) obtained for the first set of atoms (11), is eliminated by correlation with the measurement result (P12) obtained for said other set of atoms (12). ### Claim 2 (depends on 1) Method according to claim 1, wherein the first function has the expression P=P0·[1−C×cos(ΔΦ(a))] at least for the first set of atoms (11), where P denotes the measurement result, a denotes the external parameter, ΔΦ(a) is the phase shift and P0 and C are two non-zero numbers. ### Claim 3 (depends on 1) Method according to claim 1, wherein the second function is of affine function type at least for said other set of atoms (12). ### Claim 4 (depends on 3) Method according to claim 3, wherein a slope coefficient of the affine function is equal to k×T2, where T is the base time for the sequence of interactions between the atoms and the photons, and k is a modulus of a momentum received or transferred by one of the atoms during each interaction between the atoms and the photons, divided by h/(2Π), where h is Planck's constant. ### Claim 5 (depends on 1) Method according to claim 1, wherein a derivative of the measurement result (P11) obtained during a session of measurements for the first set of atoms (11), with respect to the value of the external parameter (a), is greater than the derivative of the measurement result (P12) obtained during the same session of measurements for said other set of atoms (12), also with respect to the value of the external parameter, in absolute values. ### Claim 6 (depends on 1) Method according to claim 1, wherein two of the species of atoms, which are dedicated respectively to two of the sets of atoms (11, 12) used in one and same session of measurements, are the rubidium isotopes 85 and 87, or respective isotopes of rubidium and caesium, or respective isotopes of rubidium and potassium. ### Claim 7 (depends on 1) Method according to claim 1, wherein the external parameter (a) is a gravitational field coordinate or a coordinate of an acceleration that atoms are subjected to. ### Claim 8 Apparatus for measurement by atomic interferometry comprising: a source of atoms (100) suitable for producing at least two sets of atoms (11, 12), with the atoms of each set of atoms that are of a species dedicated to said set of atoms and different from the species of atoms of each other set of atoms; means (101-103) suitable for producing conditions of atomic interference for each set of atoms (11, 12), in such a way that said conditions are produced for each set of atoms throughout a volume that is associated with said set of atoms and that contains at least one point in common with the volume associated with each other set of atoms, and are produced between a start time point and an end time point respectively before and after an intermediate time point that is common to all the sets of atoms, so as to constitute a session of measurements; a detection device, which is arranged to provide measurement results (P11, P12) respectively and independently for all the sets of atoms (11, 12) of each session of measurements; and an analysis unit, which is suitable for calculating at least one value of an external parameter (a) from each measurement result (P11, P12), in which each measurement result (P11, P12) varies according to a first function of a phase shift that appeared for the corresponding set of atoms (11, 12) during formation of the atomic interference, and said phase shift is itself a second function of the external parameter (a), said first function being alternately increasing and decreasing for at least a first (11) of the sets of atoms so that one and same measurement result (P11) that is obtained for said first set of atoms corresponds to several possible values of the external parameter (a) within a non-zero exploration interval, and said second function having, at least for one other (12) of the sets of atoms different from said first set of atoms (11), a derivative with respect to the value of the external parameter (a), that depends on at least one factor selected from a base time (T) for a sequence of interactions between the atoms and photons, and a number of photons involved in a multiphoton interaction, said sequence of interactions or said multiphoton interaction being implemented in order to form the atomic interference of said other set of atoms, the apparatus being characterized in that it is suitable for fixing a value of the factor so that, for one and same session of measurements, the measurement result (P12) that is obtained for said other set of atoms (12) corresponds to a single value of the external parameter (a) within the exploration interval. ### Claim 9 (canceled) ### Claim 10 (depends on 8) Apparatus according to claim 8, in which for each session of measurements, the conditions of atomic interferences are produced for all the sets of atoms (11, 12) using a single laser source assembly (102, 103), that is common to said sets of atoms. ### Claim 11 (depends on 8) Apparatus according to claim 8, forming an accelerometer, a gravimeter or a gyrometer. ### Claim 12 (depends on 2) Method according to claim 2, wherein the second function is of affine function type at least for said other set of atoms (12). ### Claim 13 (depends on 2) Method according to claim 2, wherein a derivative of the measurement result (P11) obtained during a session of measurements for the first set of atoms (11), with respect to the value of the external parameter (a), is greater than the derivative of the measurement result (P12) obtained during the same session of measurements for said other set of atoms (12), also with respect to the value of the external parameter, in absolute values. ### Claim 14 (depends on 3) Method according to claim 3, wherein a derivative of the measurement result (P11) obtained during a session of measurements for the first set of atoms (11), with respect to the value of the external parameter (a), is greater than the derivative of the measurement result (P12) obtained during the same session of measurements for said other set of atoms (12), also with respect to the value of the external parameter, in absolute values. ### Claim 15 (depends on 4) Method according to claim 4, wherein a derivative of the measurement result (P11) obtained during a session of measurements for the first set of atoms (11), with respect to the value of the external parameter (a), is greater than the derivative of the measurement result (P12) obtained during the same session of measurements for said other set of atoms (12), also with respect to the value of the external parameter, in absolute values. ### Claim 16 (depends on 2) Method according to claim 2, wherein two of the species of atoms, which are dedicated respectively to two of the sets of atoms (11, 12) used in one and same session of measurements, are the rubidium isotopes 85 and 87, or respective isotopes of rubidium and caesium, or respective isotopes of rubidium and potassium. ### Claim 17 (depends on 3) Method according to claim 3, wherein two of the species of atoms, which are dedicated respectively to two of the sets of atoms (11, 12) used in one and same session of measurements, are the rubidium isotopes 85 and 87, or respective isotopes of rubidium and caesium, or respective isotopes of rubidium and potassium. ### Claim 18 (depends on 4) Method according to claim 4, wherein two of the species of atoms, which are dedicated respectively to two of the sets of atoms (11, 12) used in one and same session of measurements, are the rubidium isotopes 85 and 87, or respective isotopes of rubidium and caesium, or respective isotopes of rubidium and potassium. ### Claim 19 (depends on 5) Method according to claim 5, wherein two of the species of atoms, which are dedicated respectively to two of the sets of atoms (11, 12) used in one and same session of measurements, are the rubidium isotopes 85 and 87, or respective isotopes of rubidium and caesium, or respective isotopes of rubidium and potassium. ### Claim 20 (depends on 2) Method according to claim 2, wherein the external parameter (a) is a gravitational field coordinate or a coordinate of an acceleration that atoms are subjected to. ### Claim 21 Method of measurement by atomic interferometry, in which each session of measurements is executed with at least two sets of atoms (11, 12) each subjected to conditions of formation of an atomic interference, comprising: providing an apparatus for measurement by atomic interferometry comprising: a source of atoms (100) suitable for producing at least two sets of atoms (11, 12), with the atoms of each set of atoms that are of a species dedicated to said set of atoms and different from the species of atoms of each other set of atoms; means (101-103) suitable for producing conditions of atomic interference for each set of atoms (11, 12), in such a way that said conditions are produced for each set of atoms throughout a volume that is associated with said set of atoms and that contains at least one point in common with the volume associated with each other set of atoms, and are produced between a start time point and an end time point respectively before and after an intermediate time point that is common to all the sets of atoms, so as to constitute a session of measurements; a detection device, which is arranged to provide measurement results (P11, P12) respectively and independently for all the sets of atoms (11, 12) of each session of measurements; and an analysis unit, which is suitable for calculating at least one value of an external parameter (a) from each measurement result (P11, P12), in which each measurement result (P11, P12) varies according to a first function of a phase shift that appeared for the corresponding set of atoms (11, 12) during formation of the atomic interference, and said phase shift is itself a second function of the external parameter (a), said first function being alternately increasing and decreasing for at least a first (11) of the sets of atoms so that one and same measurement result (P11) that is obtained for said first set of atoms corresponds to several possible values of the external parameter (a) within a non-zero exploration interval, and said second function having, at least for one other (12) of the sets of atoms different from said first set of atoms (11), a derivative with respect to the value of the external parameter (a), that depends on at least one factor selected from a base time (T) for a sequence of interactions between the atoms and photons, and a number of photons involved in a multiphoton interaction, said sequence of interactions or said multiphoton interaction being implemented in order to form the atomic interference of said other set of atoms, the apparatus being characterized in that it is suitable for fixing a value of the factor so that, for one and same session of measurements, the measurement result (P12) that is obtained for said other set of atoms (12) corresponds to a single value of the external parameter (a) within the exploration interval; and using the apparatus to perform said method of measurement, wherein: the atoms of each set of atoms (11, 12) being of a species dedicated to said set of atoms and different from the species of atoms of each other set of atoms, method in which, for each session of measurements, said conditions are produced for each set of atoms (11, 12) throughout a volume that is associated with said set of atoms and that contains at least one point in common with the volume associated with each other set of atoms, and are produced between a start time point and an end time point respectively before and after an intermediate time point that is common to all the sets of atoms, and in which a measurement result (P11, P12) is obtained in each session of measurements independently for each set of atoms (11, 12), each measurement result varying according to a first function of a phase shift that appeared for the set of atoms during the formation of the atomic interference, and said phase shift itself being a second function of an external parameter (a) a value of which is sought, said first function being alternately increasing and decreasing for at least a first (11) of the sets of atoms so that a measurement result (P11) that is obtained for said first set of atoms corresponds to several possible values of the external parameter (a) within a non-zero exploration interval, and said second function having, for at least one other (12) of the sets of atoms different from said first set of atoms (11), a derivative with respect to the value of the external parameter (a), that depends on at least one factor selected from a base time (T) for a sequence of interactions between the atoms and photons, and a number of photons involved in a multiphoton interaction, said sequence of interactions or said multiphoton interaction being implemented in order to form the atomic interference of said other set of atoms, wherein a value of the factor is selected in order to carry out a session of measurements, so that the measurement result (P12) that is obtained for said other set of atoms (12) corresponds to a single value of the external parameter (a) within the exploration interval, so that an indetermination between several values of the external parameter (a) that exists from the measurement result (P11) obtained for the first set of atoms (11), is eliminated by correlation with the measurement result (P12) obtained for said other set of atoms (12).