Four-port atomic gyroscope

Abstract

The present invention is entitled "Four-Port Atomic Gyroscope". Apparatus and methods for a four-port atomic gyroscope are disclosed. Due to its four ports, the output of the four-port atomic gyroscope is separated from the input so as to increase the sensitivity of the atomic gyroscope. Therefore, small changes in the rotation rate of the central axis of the optical waveguide loop around the four-port atomic gyroscope can be detected.

Description

Background Art

[0001] The navigation market is moving towards small gyroscopes without sacrificing scale factor or stability. Atomic gyroscopes offer high throughput (for high signal-to-noise ratio) and good stability of signal generating objects by referencing the scale factor of the light wavelength. Atomic gyroscopes are navigation instruments used to measure the rate of rotation around an axis of rotation. Using the Sagnac effect, the phase shift of the atomic wave function is calculated. The rate of rotation of the gyroscope is proportional to the phase shift of the atomic wave function.

[0002] U.S. Patent No. 9,766,071 (hereinafter referred to as the "'071 patent") discloses a diverging waveguide atomic gyroscope. The entire contents of the '071 patent are incorporated herein by reference. The '071 patent discloses trapping and cooling atoms so that the atoms move along the surface of a waveguide terminated by a waveguide loop, initializing the state of the atoms, and splitting the wave function of the atoms into two halves that travel in different directions around the waveguide loop. The components of the wave function traveling in each waveguide receive relative phase differences based on rotations around the central axis of the waveguide loop. The two halves are combined in the waveguide. The relative overall characteristics of the two halves of the atomic wave function determine the rate of rotation around the axis of the loop.

[0003] Thus, the waveguide loop has a single port through which the wave function enters the loop and through which the wave function leaves the loop. The optical signal used to trap the atoms at the surface of the waveguide is subject to an undesirable phase shift, for example due to a differential Stark shift, which interferes with the characterization of the relative population of the two halves of the atomic wave function. As a result, undesirable bias errors may be introduced into the gyroscope's measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Understanding that the drawings depict only exemplary embodiments and are not therefore to be considered limiting of the scope of the invention, the exemplary embodiments will be described with additional specificity and detail through the use of the accompanying drawings, in which:

[0005] Figure 1 is a cross-sectional view showing one embodiment of a waveguide having a waveguide potential energy minimum for atoms above a surface of the waveguide;

[0006] Figure 2A A block diagram showing one embodiment of a four-port atomic gyroscope;

[0007] Figure 2B A diagram showing one embodiment of a portion of a four-port atomic gyroscope;

[0008] Figure 3A An embodiment of four ports is shown;

[0009] Figure 3B Another embodiment of four ports is shown; and

[0010] Figure 4 An exemplary method of operation of a four-port atomic gyroscope is shown.

[0011] According to common practice, the various features described are not necessarily drawn to scale, instead emphasis is placed on specific features relevant to the exemplary embodiments. Summary of the invention

[0012] The present invention provides a method. The method comprises: introducing an alkali atom flow into at least one outer surface of an input optical waveguide; generating a red-blue light evanescent well above at least one outer surface of the input optical waveguide by introducing a red detuned optical signal and a blue detuned optical signal into the input optical waveguide, wherein the alkali atom flow moves parallel to the central axis of the input optical waveguide and is suspended in the red-blue light evanescent well; setting the electronic state of the alkali atoms in the alkali atom flow to a known electronic ground state configuration by applying a pumping light beam orthogonal to the alkali atom flow; measuring a first amplitude of light emitted from the alkali atom flow when the atomic state is set by the pumping light beam; and splitting the quantum mechanical wave function of the alkali atoms of the alkali atom flow into at least a first half-wave function flow and a second half-wave function flow by applying at least one Bragg optical beam including a Bragg optical pulse to the alkali atom flow, wherein the first half-wave function flow moves in the red-blue light evanescent well above at least one outer surface of the optical waveguide loop in a first direction and the second half-wave function flow moves in a second direction. The invention relates to a method for producing an optical waveguide having a first wave function and a second wave function, wherein the first wave function and the second wave function are respectively moved in a red-blue light evanescent well above at least one outer surface of the optical waveguide loop, wherein the second direction is opposite to the first direction; after the first wave function and the second wave function have each traversed the optical waveguide loop, recombining the first wave function and the second wave function into a recombined base atom; emitting a stream of some of the recombined base atoms toward an output optical waveguide; applying an optical pumping signal or another optical measurement signal to the stream of some of the recombined base atoms moving in the red-blue light evanescent well above and along at least one outer surface of the output optical waveguide; measuring a second amplitude of light emitted from the stream of some of the recombined base atoms moving in the red-blue light evanescent well above and along at least one outer surface of the output optical waveguide while applying the optical pumping signal or the other optical measurement signal; and determining a rotation rate about a central axis of the optical waveguide loop based on the measured first amplitude and the measured second amplitude. DETAILED DESCRIPTION

[0013] In the following detailed description, reference is made to the accompanying drawings which form a part thereof, and in which specific illustrative embodiments are shown by way of illustration. However, it should be understood that other embodiments may be utilized, and that logical, mechanical, and electrical changes may be made. In addition, the methods presented in the drawings and the specification should not be interpreted as limiting the order in which the various steps may be performed. Therefore, the following detailed description should not be considered to have a limiting meaning.

[0014] A four-port atomic gyroscope is then described. A four-port atomic gyroscope using Bragg interferometry overcomes the above problems. Atom interferometers can be used to perform inertial sensing. Within the category of atom interferometers for inertial sensing, there are at least two different approaches: (1) free space approaches, where atoms are launched or held in free space and probed with lasers; and (2) waveguide approaches, where atoms are shuttled along a waveguide. In either case, atoms can be interferometrically measured for rotation sensing.

[0015] Figure 1 is a cross-sectional diagram illustrating one embodiment of an optical waveguide 100 having an electric potential minimum (or well) 112 for atoms above an outer surface 114 of the optical waveguide 100. The waveguides described herein may be magnetic or optical; however, optical waveguides are shown for teaching purposes.

[0016] In an exemplary embodiment, the waveguide 100 is a planar optical waveguide on a substrate 116 that guides atoms above the substrate 116. In an exemplary embodiment, the substrate 116 is, for example, a silicon substrate; however, other substrates may also be used. The substrate 116 and the optical waveguide 100 may partially or entirely comprise an integrated circuit. In an exemplary embodiment, the waveguide 100 on the substrate is a silicon nitride ridge waveguide. However, waveguides formed of other materials using different structures may be used. Alternatively, the optical waveguide 100 may be an optical fiber; in this case, the substrate 116 is not required.

[0017] By appropriately selecting two different optical signals traveling down the optical waveguide, the evanescent fields of those optical signals around the optical waveguide 100 become traps for atoms traveling above the optical waveguide 100, guiding the atoms along a path above the waveguide 100, but without contacting the physical surface 104 of the optical waveguide 100. In an exemplary embodiment, a red detuned optical signal is generated (e.g., using a red detuned laser detuned below the atomic resonance frequency of the atoms located above the optical waveguide 100), and a blue detuned optical signal is generated (e.g., using a blue detuned laser detuned above the atomic resonance frequency of the atoms located above the optical waveguide 100). Each resonance frequency of an alkali atom is a frequency where light energy causes the electrons of the alkali atom to change electronic states. The potential minimum or trap formed by the evanescent fields of the red detuned optical signal and the blue detuned optical signal may also be referred to herein as a red-blue light evanescent trap.

[0018] The evanescent field of the red detuned optical signal is attractive to the atoms (and therefore also referred to as the attractive evanescent field 118), so that it creates a potential minimum that pulls the atoms toward the optical waveguide 100. In contrast, the evanescent field of the blue detuned optical signal is repulsive to the atoms (and therefore also referred to as the repulsive evanescent field 110), so it pushes the atoms away from the optical waveguide 100.

[0019] In an exemplary embodiment, the attractive evanescent field 118 generated by the red detuned optical signal and the repulsive evanescent field 110 generated by the blue detuned optical signal extend above the outer surface 114 of the optical waveguide 100. The evanescent field of the blue detuned optical signal decays faster than the evanescent field of the intensity (or power) of the red detuned optical signal. In an exemplary embodiment, the attractive evanescent field 108 and the repulsive evanescent field 110 both extend several hundred nanometers above the outer surface 114 of the optical waveguide 100. The intensity of each of the attractive evanescent field 118 and the repulsive evanescent field 110 decreases with distance above the outer surface 114 of the waveguide 100. This causes atoms above the outer surface 114 of the optical waveguide 100 to be subjected to both the attractive force of the attractive evanescent field 118 generated by the red detuned optical signal and the repulsive force of the repulsive evanescent field 110 generated by the blue detuned optical signal. If only the attractive evanescent field 118 generated by the red detuned optical signal is present, the atoms will be pulled down to the outer surface 114 of the waveguide 100, where they will stick, bounce off, or otherwise be lost. The blue detuned optical signal (repulsive optical signal) has a repulsive evanescent field 110 that does not extend as far above the outer surface 114 of the optical waveguide 100 as the attractive evanescent field 118 generated by the red detuned optical signal (attractive optical signal). The attractive evanescent field 118 generated by the red detuned optical signal pulls the atoms toward the surface 104 of the waveguide 100. The atoms are also pulled toward the center of the attractive evanescent field 118 generated by the red detuned optical signal to provide a trapping potential transverse to the substrate surface; therefore, the atoms are trapped in two orthogonal directions. As the atoms get closer to the outer surface 114 of the optical waveguide 100, they begin to experience repulsive forces from the repulsive evanescent field 110 generated by the blue detuned optical signal, which pushes the atoms away from the outer surface 114 of the optical waveguide 100. In response to these attractive and repulsive forces, the atoms find the red-blue evanescent well 112 above the surface 104 of the optical waveguide 100. In an exemplary embodiment, the red-blue evanescent well 112 is fifty to three hundred nanometers above the outer surface 114 of the optical waveguide 100; however, this range is exemplary, and the range of distances may vary depending on the atoms used (e.g., alkali atoms), the design of the four-port atomic gyroscope, and / or the intensity or frequency of the red-detuned optical signal and the blue-detuned optical signal.

[0020] In an exemplary embodiment, the wavelengths of the red detuned light signal and the blue detuned light signal differ by many nanometers and are both relatively detuned away from the atomic resonance. In the case of a rubidium alkali atom, the resonance associated with the change in the electronic energy level of the rubidium atom has a wavelength of 780 nm. In this case, the blue detuned light signal may be about 632 nanometers, which is a convenient diode wavelength. In contrast, the red detuned light signal may be about 852 nanometers, which is another useful diode wavelength. Note that other wavelengths may be used.

[0021] In an exemplary embodiment, for a red detuned optical signal (having a frequency lower than resonance), the AC Stark effect shifts the atomic energy downward, while for a blue detuned optical signal (having a frequency higher than resonance), it shifts the atomic energy upward. In the case where both 852 nm and 632 nm (or other suitable) light sources are coupled into the waveguide 100, the blue detuned light increases the atomic energy and pushes the atoms away from the outer surface 114 of the optical waveguide 100, while the red detuned light pulls the atoms toward the outer surface 114 of the optical waveguide 100. The light sources may be arranged so that a red and blue light evanescent well is created around the outer surface 114 that suspends the atoms above the outer surface 114 of the optical waveguide 100 far enough away from the outer surface 114 of the optical waveguide 100 that the atoms do not contact, collide with, or scatter on the outer surface 114 of the optical waveguide 100. Instead, the atoms move longitudinally above the surface 104 of the waveguide 100 so that they are confined by the optical potential but can move freely along the direction of the optical waveguide 100.

[0022] Figure 2A A block diagram of one embodiment of a four-port atomic gyroscope 220A is shown. The term "four-port" refers to two ports of the optical waveguide loop 222 (and thus an open optical waveguide loop) and two other ports: the second end of the first input optical waveguide 200A and the end of the output optical waveguide 200B, such as the input end or port. These four ports will be described subsequently. In an exemplary embodiment, the optical waveguide loop 222 has a circular circumference centered on the central axis 298.

[0023] The illustrated embodiment of the four-port atomic gyroscope 200 includes an atomic well 221, a first input optical waveguide 200A, an output optical waveguide 200B, an optical waveguide loop 222, a red detuned laser 226 configured to generate a red detuned optical signal (or optical beam) 226A, a blue detuned laser 228 configured to generate a blue detuned optical signal (or optical beam) 228A, a second input optical waveguide 228B, a first Bragg laser 223A configured to generate a first Bragg optical signal 223A-1, a second Bragg laser 223B configured to generate a second Bragg optical signal 233B-1, and an optical baffle 229.

[0024] In an exemplary embodiment, the red detuned laser 226 (and the red detuned optical signal 226A) can be coupled to the first input optical waveguide 200A; the blue detuned laser (and the blue detuned optical signal 228A) can be coupled to the second input optical waveguide 228B, and coupled to the first input optical waveguide 200A through the optical coupler 228C. However, alternatively, the blue detuned laser 228 can be coupled to the first input optical waveguide 200A, and the red detuned laser 226 can be coupled to the second input optical waveguide 228B.

[0025] Optionally, some or all of the aforementioned components are implemented in a substrate 216 (e.g., an integrated circuit). The substrate may be silicon or other materials, such as glass or other optically transparent materials (e.g., an optical window). If a substrate 216 is used, some or all of the waveguides, couplers, and optical waveguide circuits 222 may be implemented using planar optical waveguides fabricated on the substrate.

[0026] Alternatively, one or more of the aforementioned devices may be implemented with other forms of waveguides, such as optical fibers. Further, for example, if the substrate 216 is not used, some optical waveguides (except the first input optical waveguide 200A, the output optical waveguide 200B, and the optical waveguide loop 222) do not need to be used, and the optical waveguides may be replaced by free space. These include, for example, waveguides carrying one or more cooling optical signals (if used), pump optical signals, and / or measurement optical signals (if used).

[0027] In other exemplary embodiments, the red-detuned optical signal 226A and the blue-detuned optical signal 226B are coupled into the first input optical waveguide 200A in various other ways, as shown in the '071 patent. For example, the red-detuned optical signal 226A and the blue-detuned optical signal 226B may be injected into the input 200A-1 of the first input optical waveguide 200A; thus, the optical coupler 228C (and possibly the second input optical waveguide 228B) is not required. Alternatively, the red-detuned optical signal 226A and / or the blue-detuned optical signal 226B may be coupled to the first input optical waveguide 200A via one or more directional optical couplers (e.g., via a red-detuned directional optical coupler and / or a blue-detuned directional optical coupler, respectively). Further, alternatively, one directional optical coupler may be used to couple both signals. Note that although the red detuned optical signal 226A and the blue detuned optical signal 226B are described above as being injected and / or coupled into the first input optical waveguide 200A, each of such optical signals may be coupled and / or injected into the output optical waveguide 200B and / or the optical waveguide loop 222 in other manners.

[0028] Regardless of how they are coupled, the red detuned optical signal 226A and the blue detuned optical signal 228A travel through the first input optical waveguide 200A, the output optical waveguide 200B, and the optical waveguide loop 222, and generate a red and blue light evanescent well. Therefore, the red and blue light evanescent well exists above at least a portion of the outer surface of each of the first input optical waveguide 200A, the output optical waveguide 200B, and the optical waveguide loop 222.

[0029] Atom well 221 contains alkali atoms 221A which emit a continuous stream 221A-1 of alkali atoms 221A (moving with a velocity distribution based on the alkali atom temperature) toward input 200A-1 of the input optical waveguides. Upon reaching the first input optical waveguide 200A, the alkali atoms 221A travel from the first input optical waveguide 200A to the optical waveguide loop 222 outside the outer surface.

[0030] Back to Figure 2A , the alkali atom 221A may be, for example, one of a rubidium atom or a cesium atom; however, the alkali atom 221A may be one of any other type of alkali atom. For example, if a rubidium atom is used in the atomic well 221, the resonant frequency associated with the change in the electronic energy level of rubidium has a wavelength of 780 nm. Therefore, the red detuned optical signal 226A, the blue detuned optical signal 228A, and the Bragg optical signal 223A are configured to have a wavelength at or near the resonant frequency associated with the change in the electronic energy level of the alkali atom 221A in the atomic well 221.

[0031] The atom trap 221 may be, for example, a magneto-optical trap or an optical dipole. The atom trap 221 cools and concentrates the alkali atoms 221A, for example, in a Bose-Einstein condensate or a cold-hot ensemble. If the atom trap 102 is a magneto-optical trap, the atom trap 102 may be enabled and disabled by respectively activating and deactivating three orthogonal optical signals generated by a laser, the three orthogonal optical signals being directed to the center of the atom trap 221 and the DC magnetic field in the atom trap 221; the wavelength of the orthogonal optical signal is a wavelength at or near the resonant frequency associated with the change in the electronic energy level of the alkali atoms 221A in the atom trap 221.

[0032] The stream 221A-1 of alkali atoms 221A can be coupled to the outside surface of the first input optical waveguide 200A in different ways. In an exemplary embodiment, the stream 221A-1 can be directed to an exposed first end (or port) 295 of the first input optical waveguide 200A (e.g., at the edge of the substrate 216), which is opposite to the second end (or port) of the first input optical waveguide 200A coupled to the optical waveguide loop 222. However, this may not effectively capture the alkali atoms in the red-blue light evanescent well at the first input optical waveguide 200A. Therefore, other techniques can be used to improve the efficiency of the transfer of alkali atoms 221A to the red-blue light evanescent well at the input optical waveguide. By improving the transfer efficiency of the interferometer and therefore the gyroscope, the efficiency and sensitivity can be improved.

[0033] Figure 2B A diagram showing one embodiment of a portion of a four-port atomic gyroscope 220B is shown. Figure 2BAn embodiment for improving the efficiency of the red and blue light evanescent traps around a portion 200A-2 of the input optical waveguide for improving the alkali atom flow is shown. These techniques can be used in other gyroscope embodiments. First, the red detuned optical signal 226A is coupled into the first input optical waveguide 200A so that it propagates in two directions. This can be achieved in different ways. For example, the end of the first portion 200A-1 of the first optical waveguide 200A is split into two parts, wherein each split end is directly connected to the second portion 200A-2 of the first optical waveguide 200A. Alternatively, the end portion of the first portion 200A-1 of the first optical waveguide 200A is coupled to the second portion 200A-1 of the first optical waveguide 200A by a bidirectional optical coupler (e.g., formed by two back-to-back directional optical couplers). As a result, the red detuned optical signal 226A is directed in two directions in the second portion 200A-1 of the first input optical waveguide 200A (e.g., toward the exposed end 295 (e.g., at the edge of the substrate 216) of the second portion 200A-2 configured to receive the stream 221A-1, and toward the optical waveguide loop 222. The emission (or diverging) field of the red detuned optical signal 226A emitted from the end of the second portion 200A-2 attracts the alkali atoms 221A toward the exposed end 295 of the first input optical waveguide 200A and into the stream 221A-1.

[0034] Alternatively, a grating coupler 297, for example, on the substrate 216, can terminate the exposed end 295 of the first input optical waveguide 200A. The grating coupler 297 emits a red detuned optical signal 226A in the direction of the input flow 221A-1 toward the alkali atoms 221A. The grating coupler 297 can be formed by periodic notches of the first input optical waveguide 200A. The periodic notches cause diffraction so that the red detuned optical signal 226A′-1 is emitted into free space away from the grating coupler 297 at a certain angle to the outer surface of the grating coupler 297 (e.g., the first input optical waveguide 200A that is notched). The diameter of the emitted red detuned optical signal 226A′-1 increases with the distance from the grating coupler 297. The angle depends on the dimensions of the grating, such as the width, depth, and pitch. By directing stream 221A-1 of alkali atoms 221A toward emitted red detuned optical signal 226A'-1, and red detuned optical signal 226A'-1 toward stream 221A-1, transfer efficiency of alkali atoms 221A is improved. Note that bidirectional coupler implementations may be implemented with or without optical coupler grating implementations.

[0035] Using one of the aforementioned techniques, the stream 221A-1 of alkali atoms 221A is effectively focused from free space towards the grating coupler 297. Thus, the second portion 200A-2 of the first input optical waveguide 200A evanescently traps the red and blue light.

[0036] Back to Figure 2A At least one cooling beam (or signal) is used to reduce the movement of the alkali atoms 221A in at least one direction that is transverse to the direction of movement of the stream 221A-1 along the red and blue light evanescent trap. In this way, the efficiency and sensitivity of the interferometer and therefore the gyroscope are improved. The transverse axes are orthogonal to each other and to the direction of movement of the stream 221A-1.

[0037] The lateral motion may occur in either a positive or negative direction along the lateral axis. Thus, to compensate for each such direction, one or two cooling beams (or signals) may be applied. When two cooling beams are applied, one cooling beam is applied in the positive direction and one beam is applied in the negative direction. Each such cooling beam may be generated by a common or a different laser.

[0038] In order to reduce lateral motion in two directions on an axis orthogonal to the traveling direction of the flow 221A-1, a counter-propagating first cooling beam (or signal) 291A and a second cooling beam (or signal) 291B are applied along a first axis orthogonal to the traveling direction of the flow 221A-1. If the first input optical waveguide 200A is formed on the substrate 216, the counter-propagating first cooling beam 291A and the second cooling beam 291B can be generated by corresponding lasers, each of which is coupled to a unique end of an optical waveguide on the substrate 216 (for example, on a plane parallel to the surface of the substrate 216) that passes orthogonally through the first input optical waveguide 200A. The counter-propagating first cooling beam 291A and the second cooling beam 291B are configured to be orthogonal to the flow 221A-1.

[0039] Further, a single third cooling beam (or signal) 291 is applied in free space or through an optical fiber orthogonal to the surface of the substrate 216 (and therefore orthogonal to the two counter-propagating beams 291A, 291B and the stream 221A-1). The third cooling beam 291C and its reflection from the surface of the substrate 216 (fourth cooling beam (or signal) 291D) reduce atomic movement on a second axis orthogonal to the direction of travel of the stream 221A-1 and orthogonal to the first orthogonal axis. Alternatively, if the substrate 216 is not used, the two counter-propagating first cooling beams 291A and second cooling beams 291B and the single cooling beam 291C (and the corresponding counter-propagating cooling beams) can be applied through free space and / or through an optical fiber orthogonal to the stream 221A-1.

[0040] Optionally, the speed of the alkali atoms 221A in the stream 221A- 1 can be adjusted. By choosing the appropriate speed, interferometer and therefore gyroscope, the efficiency and sensitivity can be improved.

[0041] In order to adjust the velocity distribution of the alkali atoms 221A in the stream, another pair of fourth cooling beams 291E and fifth cooling beams 291F may be applied to the stream 221A-1. The fourth cooling beam 291E and the fifth cooling beam 291F form a plane with the stream 221A-1. The fourth cooling beam 291E and the fifth cooling beam 291F are co-incident with the stream 221A-1, have opposite vector components parallel to the direction of travel of the stream 221A-1, and may have different or the same absolute values ​​of the angles of incidence. However, for didactic reasons, an embodiment is described in which each of the fourth cooling beam 291E and the fifth cooling beam 291F is co-incident with the stream 221A-1 at an angle θ and an angle -θ, respectively. The frequency of each of the fourth cooling beam 291E and the fifth cooling beam 291F. The velocity of the stream 221A-1 is equal to d / (2*k*cos(θ)), where d is the frequency difference between the fourth cooling beam 291E and the fifth cooling beam 291F. The fourth cooling beam 291E has a higher frequency than the fifth cooling beam 291E, and k=2*π / λ, where λ is the average wavelength of the fourth cooling beam 291E and the fifth cooling beam 291F, or one of the wavelengths of the fourth cooling beam 291E and the fifth cooling beam 291F.

[0042] The electronic states of all alkali atoms in the alkali atom 221A in the red-blue light evanescent trap are set to single electronic states, rather than randomly distributed electronic states. By setting the electronic states of all alkali atoms in the alkali atom 221A to single electronic states, the efficiency and sensitivity of the interferometer and thus the gyroscope are improved.

[0043] To set the electronic states of all alkali atoms 221a to a single electronic state, an evanescent field of a pump beam (or signal) 225A (having a frequency substantially corresponding to the desired electronic ground state of the alkali atoms 221A) is applied to the stream 221A. The pump beam 225A is generated by a pump laser 225. The pump beam 225A can be applied through free space or an optical waveguide orthogonal to the stream 221A-1. For example, the optical waveguide can be an optical fiber or optical waveguide 225B in the substrate 216 that is orthogonal and passes through the first input optical waveguide 200A.

[0044] The first light detector 293A (eg, a photodetector) is placed near, for example, above, the intersection of the pump beam 225A and the flow 221A. The first light detector detects the amplitude A of the light generated by the fluorescence of the interaction of the pump beam 225A and the flow. T . A T represents the population of alkali atoms 221A entering the four ports 299 from a first input optical waveguide 200A (eg, described elsewhere herein).

[0045] At the four ports 299 (at the junction of the first input optical waveguide 200A, the output optical waveguide 200B and the optical waveguide loop 222), at least one Bragg beam (or signal) is applied as a flow 221A-1 orthogonal to the red and blue light evanescent well. For teaching purposes, two counter-propagating Bragg beams will be described. The first counter-propagating Bragg beam (or signal) 223A-1 and the second counter-propagating Bragg beam (or signal) 223B-1 are generated by one or more lasers (e.g., the first Bragg laser 223A and the second Bragg laser 223B), respectively. The first counter-propagating Bragg beam 223A-1 and the second counter-propagating Bragg beam 223B-1 are transmitted to the four ports 299 through an optical waveguide or free space. The optical waveguide can be an optical fiber or an optical waveguide formed on the substrate 216.

[0046] The four ports 299 can be implemented in different ways. The four ports 299 should be implemented in a way that does not significantly affect (eg, interfere with) the red and blue evanescent wells.

[0047] Figure 3A One embodiment of four ports 399A is shown. Figure 3A In the embodiment, four ports 399A are formed by connecting the output port of the input waveguide 300A, the input port of the output optical waveguide 300B, the first port of the optical waveguide loop 322, and the second port of the optical waveguide loop 322. All four ports are substantially in the same plane. The four ports 399A do not substantially affect the application of the red and blue light evanescent wells or Bragg light signals 223A-1, 223B-1.

[0048] Figure 3B Another embodiment of four ports 399B is shown. Figure 3B In the embodiment, the four ports 399A are formed by a first connecting optical waveguide between the output port of the input waveguide 300A and the second port of the optical waveguide loop 322, which is substantially parallel and adjacent to the second connecting optical waveguide between the input port of the output optical waveguide 300B and the first port of the optical waveguide loop 322. The first connecting optical waveguide and the second connecting optical waveguide should be close enough to couple optical signals between each other, but not in physical contact with each other. As a result, a single red and blue evanescent light trap is above at least one outer surface of the optical waveguides forming the first connecting optical waveguide and the second connecting optical waveguide. All four ports are substantially in the same plane. The four ports 399B do not substantially affect the application of the red and blue evanescent light traps or the Bragg optical signals 223A-1, 223B-1. The four ports can be implemented in other ways as described above.

[0049] Back to Figure 2A, each of the counter-propagating Bragg beams 223A-1, 223B-1 includes a Bragg optical pulse. When the beam is transmitted through the optical waveguide, the Bragg optical pulses of the counter-propagating Bragg beams 223A-1, 223B-1 pass through the four ports 299 to generate the evanescent field of the counter-propagating Bragg beams 223A-1, 223B-1, which are coupled to the alkali atoms 221A (or wave functions) traveling along the four ports 299. When the beam is transmitted through free space, the counter-propagating Bragg beams 223A-1, 223B-1 pass through the four ports 299 to generate the field of the counter-propagating Bragg beams 223A-1, 223B-1, which are coupled to the alkali atoms 221A (or wave functions) traveling along the four ports 299.

[0050] The Bragg optical pulse is designed to split the wave function of the alkali atom 221A into two parts, which have different motion states but maintain the same electronic state. The amplitude, phase and frequency of the optical pulse required to split the atomic wave function of the alkali atom into two such parts can be determined using the Schrödinger equation. When split, each part can have equal or unequal population relative to the other part.

[0051] Half of the atomic wave function travels clockwise 222A around the optical waveguide loop 222. The other half of the atomic wave function travels counterclockwise 222B around the optical waveguide loop 222.

[0052] The Bragg optical pulse is also configured to recombine the first half-wave function and the second half-wave function into recombined base atoms after the first half-wave function and the second half-wave function have traversed the optical waveguide loop 222, wherein some of the recombined base atoms exit above and along the outer surface of the output optical waveguide and other recombined base atoms exit above and along the outer surface of the input optical waveguide.

[0053] Measuring beam 294 is applied orthogonally to output optical waveguide 200B. Measuring beam 294 is generated by a laser (eg, pump laser 225 or a separate laser) and has a frequency substantially corresponding to the desired electronic state of alkali atom 221A or another electronic state of alkali atom 221A.

[0054] The second light detector 293B (e.g., a photodetector) is placed near, for example, above, the intersection of the measurement light beam (or signal) 294 and the recombinant alkali atom flow around the output optical waveguide 200B. The second light detector 293B detects the amplitude A of the light generated by the fluorescence of the interaction of the measurement light beam 294 and the recombinant alkali atoms flowing around the output optical waveguide 200B. M . A MThe ratio of the population of motion states measured by the second light detector 293B (i.e., in the output light waveguide 200B) relative to the population measured by the first light detector 293B depends on the rotation rate of the light waveguide loop 222 about the central axis 298.

[0055] Optionally, an optical baffle 229 is placed between the first input optical waveguide 200A and the output optical waveguide 200B close to each other and close to the four ports 299. The baffle 229 isolates half of the atomic wavefunction of the flow 221A in the output optical waveguide 200B from the pump beam 225A and isolates the other half of the atomic wavefunction of the flow 221A in the first input optical waveguide 200A from the measurement beam 294.

[0056] The total number and amplitude of the motion state are expressed by a periodic sine wave function with a phase shift Related:

[0057]

[0058] Wherein C is a constant depending on the overall difference of the maximum and minimum differences between the two motion states, and D is a constant depending on the background light leaking into the first light detector 293A and the second light detector 293B.

[0059] Because the change in the population (between no rotation and rotation about the central axis) is measured by correlating the change in absorption or phase delay of the third set of optical pulses to the population ratio, the phase shift between the two parts of the wave function can be easily determined. Using the Sagnac equation, the rate of rotation (Ω) about the central axis 298 of the optical waveguide loop 222 can be determined:

[0060]

[0061] Where m is the mass of the alkali atom, A is the cross-sectional area enclosed by the atomic wave function circulating in the optical waveguide loop 222, and h is Planck's constant.

[0062] Figure 4 An exemplary method 400 of operating a four-port atomic gyroscope is shown. In part, Figure 4 The method 400 shown is described herein as in reference Figures 1 to 3BThe above-mentioned devices are implemented, and it should be understood that other embodiments can be implemented in other ways. For ease of explanation, the blocks of the flowchart are arranged in a generally sequential manner; however, it should be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with these methods (and the blocks shown in the figure) can occur in a different order (for example, where at least some of the processing associated with these blocks is performed in a parallel manner and / or in an event-driven manner).

[0063] The method 400 proceeds to block 440 where a flow of alkali atoms is introduced to the outer surface of the input optical waveguide, such as by delivering the flow to the distal end of the input optical waveguide (or the distal end of a portion of the input optical waveguide). Optionally, the flow of alkali atoms may be generated by an atom trap.

[0064] The method 400 proceeds to block 442, where a red-blue evanescent well is generated above the surface of the input optical waveguide having the first evanescent field and the second evanescent field, wherein the mobile alkali atoms travel above parallel to the central axis of the input optical waveguide and are suspended in the red-blue evanescent well. In an exemplary embodiment, the red-blue evanescent well is formed by introducing a red detuned optical signal and a blue detuned optical signal into the input optical waveguide. The red detuned optical signal has a first frequency that is lower than the resonant atomic frequency of the alkali atoms above the surface of the input optical waveguide. The red detuned optical signal has a first evanescent field that extends above the input optical waveguide for a first distance greater than the second distance, and the first evanescent field attracts the atoms toward the surface of the input optical waveguide.

[0065] The blue detuned optical signal has a second frequency that is higher than the resonant atomic frequency of atoms above the surface of the input optical waveguide. The blue detuned optical signal has a second evanescent field that extends a second distance above the input optical waveguide, the second evanescent field repels alkali atoms from the surface of the input optical waveguide.

[0066] The method 400 proceeds to block 444, where the stream of alkali atoms is cooled in one direction or two opposite directions of one or two axes transverse to (or orthogonal to) the central axis of the input optical waveguide (and the axis along which the stream of alkali atoms travels. Further, optionally, the stream of alkali atoms on the axis of travel of the stream is cooled so that the stream moves with a velocity distribution.

[0067] The method 400 proceeds to box 446, where the electronic state of the alkali atoms in the mobile stream after the red and blue light evanescent trap above the input optical waveguide is set to a known electronic ground state configuration. For example, this can be achieved by applying a pump light signal to the mobile stream, wherein the frequency of the pump light signal is substantially equal to the frequency of the desired electronic ground state. In an exemplary embodiment, the known electronic ground state configuration is the lower electronic ground state of the two-electron ground state. In other embodiments, the known ground state is the higher electronic ground state of the two-electron ground state. However, any electronic ground state configuration can be used. The method 400 proceeds to box 448, where the amplitude of the light emitted from the alkali atom stream is measured when their electronic state is set (e.g., by the pump light signal).

[0068] The method 400 proceeds to block 450, wherein the quantum mechanical wave function of the flowing alkali atoms is split into at least a flow of a first group of atoms following a red-blue evanescent well above an outer surface of the optical waveguide loop in a first direction and a flow of a second group of alkali atoms following a red-blue evanescent well above an outer surface of the optical waveguide loop in a second direction. The second direction is opposite to the first direction. The phase of the first group relative to the phase of the second group depends on the rate of rotation about a central axis of the optical waveguide loop.

[0069] Method 400 proceeds to block 451, where the first half-wave function and the second half-wave function are recombined into a recombined base atom after the first half-wave function and the second half-wave function have traversed the optical waveguide loop. The recombination occurs when the first half-wave function and the second half-wave function travel around the optical waveguide loop only once.

[0070] The method 400 proceeds to block 452, where a stream of alkali atoms traveling from around the optical waveguide loop in a first direction is emitted, for example, to an output optical waveguide. The total number of atoms traveling in the output optical waveguide depends on the relative phase between the first group of atoms and the second group of atoms rotating around the optical waveguide loop. The stream of alkali atoms travels above the outer surface of the output optical waveguide. The method 400 proceeds to block 454, where an optical signal (e.g., an optical pump signal or an optical measurement signal) is applied to the emitted stream of alkali atoms, which travels, for example, along the outer surface of the output optical waveguide. The method 400 proceeds to block 456, where the amplitude of light emitted from the stream of alkali atoms traveling along the outer surface of the output optical waveguide is measured when the second optical signal is applied to them. The method 400 proceeds to block 458, where the rotation rate around the central axis of the optical waveguide loop is determined using the light amplitudes measured in blocks 448 and 456 (e.g., using the equations presented herein).

[0071] In an exemplary embodiment, the processing circuit is configured to control an embodiment of the four-port atomic gyroscope 220A, and / or determine the rotation rate around the central axis of the optical waveguide loop. In an exemplary embodiment, the processing circuit includes a software program, firmware or other computer-readable instructions for performing various methods, processing tasks, calculations and control functions used in the gyroscope, or runs with the software program, firmware or other computer-readable instructions. These instructions are generally stored on any suitable computer-readable medium for storing computer-readable instructions or data structures. The computer-readable medium can be implemented as any available medium that can be accessed by a general or special-purpose computer or processor or any programmable logic device. Suitable processor-readable media can include storage or memory media, such as magnetic or optical media. For example, the storage or memory medium can include a conventional hard disk, a compact disk read-only memory (CD-ROM), a volatile or non-volatile medium (such as a random access memory (RAM) (including but not limited to synchronous dynamic random access memory (SDRAM), double data rate (DDR) RAM, RAMBUS dynamic RAM (RDRAM), static RAM (SRAM), etc.)), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM) and a flash memory, etc. Suitable processor-readable media may also include transmission media (such as electrical, electromagnetic or digital signals) conveyed over a communications medium (such as a network and / or wireless link).

[0072] Exemplary embodiments

[0073] Embodiment 1 includes an apparatus comprising: an input optical waveguide, the input optical waveguide comprising a first end and a second end, wherein the first end is configured to receive an alkali atom flow; an optical waveguide loop, the optical waveguide loop having a first port and a second port, wherein the first port is coupled to the second end, wherein the optical waveguide loop has a central axis; a first optical detector, the first optical detector being configured to measure an amplitude of light emitted from the alkali atom flow when a pump optical signal is applied to the alkali atom flow around the input optical waveguide, wherein the pump optical signal sets an electronic ground state of the alkali atoms; an output an optical waveguide, the output optical waveguide having an end coupled to the second port; wherein the input optical waveguide, the optical waveguide loop, and the output optical waveguide each have at least one outer surface, wherein each of the outer surfaces is configured to have a red-blue light evanescent well above the corresponding outer surface, wherein the red-blue light evanescent well is configured to transmit an alkali atom flow, and wherein the red-blue light evanescent well is formed by a red-detuned optical signal and a blue-detuned optical signal; wherein the first port, the second port, the second end, and the end of the output optical waveguide are configured to receive at least one field of at least one Bragg beam, the at least one Bragg beam transmitting at least one field of ... The Bragg optical beam includes a Bragg optical pulse configured to split alkali atoms into two half-wave function streams, wherein a first half-wave function stream travels clockwise around the optical waveguide loop and a second half-wave function stream travels counterclockwise around the optical waveguide loop; wherein the Bragg optical pulse is further configured to recombine the first half-wave function and the second half-wave function into recombined alkali atoms after the first half-wave function and the second half-wave function have traversed the optical waveguide loop, wherein some of the recombined alkali atoms exit above and along an outer surface of an output optical waveguide and other recombined alkali atoms exit above and along an outer surface of an input optical waveguide; and a second optical detector configured to measure an amplitude of light emitted from the recombined alkali atom stream exiting above and along an outer surface of the output optical waveguide when a pump optical signal or another optical signal is applied to the recombined alkali atom stream exiting above and along the outer surface of the output optical waveguide, wherein the number of recombined alkali atoms exiting above and along the outer surface of the output optical waveguide depends on the rotation rate around the central axis of the optical waveguide loop.

[0074] Embodiment 2 includes the apparatus of embodiment 1, wherein the alkali atom flow around the input optical waveguide is configured to receive at least one cooling light beam after entering the red and blue light evanescent trap around the input optical waveguide.

[0075] Embodiment 3 includes the apparatus of embodiment 2, wherein the at least one cooling beam comprises at least one cooling beam configured to cool the alkali atom flow in one direction or two opposite directions of at least one axis orthogonal to the direction of travel of the alkali atom flow.

[0076] Embodiment 4 includes the apparatus of any one of embodiments 2 to 3, wherein at least one cooling beam comprises two cooling beams, the two cooling beams form a plane with the alkali atom flow, wherein each of the two cooling beams has a vector component parallel to the traveling direction of the alkali atom flow, wherein the component of one cooling beam is in an opposite direction relative to the component of the other cooling beam; and wherein the speed of the alkali atom flow depends on the incident angles of the two cooling beams relative to the alkali atom flow, the frequency difference of the two cooling beams, and the average wavelength of the two cooling beams.

[0077] Embodiment 5 includes the device of any one of embodiments 1 to 4, further comprising an optical baffle between the input optical waveguide and the output optical waveguide through the optical waveguide loop.

[0078] Embodiment 6 includes the device of any one of embodiments 1 to 5, wherein a first connecting optical waveguide between the second end of the input waveguide and the second port of the optical waveguide loop is parallel to, not in contact with, and adjacent to a second connecting optical waveguide between the end of the output optical waveguide and the first port of the optical waveguide loop, wherein a single red-blue evanescent light trap is above at least one outer surface of the optical waveguides forming both the first connecting optical waveguide and the second connecting optical waveguide.

[0079] Embodiment 7 includes the apparatus of any one of embodiments 1 to 6, wherein the grating is coupled to the first end of the input optical waveguide and is configured to emit a divergent field of a red detuned optical signal to attract the alkali atom flow to the red and blue light evanescent well.

[0080] Embodiment 8 comprises a method, comprising: introducing an alkali atom stream into at least one outer surface of an input optical waveguide; generating a red-blue light evanescent well above at least one outer surface of the input optical waveguide by introducing a red-detuned optical signal and a blue-detuned optical signal in the input optical waveguide, wherein the alkali atom stream moves parallel to a central axis of the input optical waveguide and is suspended in the red-blue light evanescent well; setting the electronic state of the alkali atoms in the alkali atom stream to a known electronic ground state configuration by applying a pump beam orthogonal to the alkali atom stream; measuring a first amplitude of light emitted from the alkali atom stream when the atomic state is set by the pump beam; splitting the quantum mechanical wave function of the alkali atoms in the alkali atom stream into at least a first half-wave function stream and a second half-wave function stream by applying at least one Bragg optical beam including a Bragg optical pulse to the alkali atom stream, the first half-wave function stream moving in a first direction in the red-blue light evanescent well above at least one outer surface of the optical waveguide loop, the second half-wave function stream moving in a first direction in the red-blue light evanescent well above at least one outer surface of the optical waveguide loop, The invention relates to a method for producing an optical waveguide having a first half-wave function and a second half-wave function, wherein the first half-wave function and the second half-wave function are respectively recombined into recombined base atoms after the first half-wave function and the second half-wave function have each traversed the optical waveguide loop; emitting a stream of some of the recombined base atoms toward an output optical waveguide; applying an optical pumping signal or another optical measurement signal to the stream of some of the recombined base atoms moving in the red-blue light evanescent well above and along at least one outer surface of the output optical waveguide; measuring a second amplitude of light emitted from the stream of some of the recombined base atoms moving in the red-blue light evanescent well above and along at least one outer surface of the output optical waveguide while applying the optical pumping signal or the other optical measurement signal; and determining a rotation rate about a central axis of the optical waveguide loop based on the measured first amplitude and the measured second amplitude.

[0081] Embodiment 9 includes the method of embodiment 8, further comprising applying at least one cooling beam to the alkali atom flow around the input optical waveguide in a direction orthogonal to the moving direction of the alkali atom flow to cool the alkali atom flow in at least one direction orthogonal to the central axis of the input light.

[0082] Embodiment 10 includes the method of any one of embodiments 8 to 9, further comprising emitting a divergent field of a red-detuned optical signal to attract the alkali atom flow to the red-blue light evanescent well.

[0083] Embodiment 11 comprises the method of any one of embodiments 8 to embodiment 10, wherein applying at least one cooling beam comprises applying a pair of cooling beams, the pair of cooling beams forming a plane with the alkali atom flow, wherein the pair of cooling beams have vector components parallel to the travel direction of the alkali atom flow, wherein the vector component of one cooling beam is in an opposite direction relative to the vector component of the other cooling beam; and wherein the speed of the alkali atom flow depends on the incident angles of the two cooling beams relative to the alkali atom flow, the frequency difference of the two cooling beams, and the average wavelength of the two cooling beams.

[0084] Embodiment 12 includes the method of any one of embodiments 8 to 11, further comprising generating a flux of alkali atoms in the atom trap.

[0085] Embodiment 13 includes a gyroscope comprising: an input optical waveguide, the input optical waveguide comprising a first end and a second end, wherein the first end is configured to receive an alkali atom stream; a red detuned laser, the red detuned laser optically coupled to the input optical waveguide and configured to generate a red detuned optical signal; a blue detuned laser optically coupled to the input optical waveguide and configured to generate a blue detuned optical signal; an optical waveguide loop, the optical waveguide loop having a first port and a second port, wherein the first port is coupled to the second end, wherein the optical waveguide loop has a central axis; a first optical detector, the first optical detector configured to measure light emitted from the alkali atom stream when a pump optical signal is applied to the alkali atom stream an input optical waveguide including a first end and a second end, wherein the first end is configured to receive the alkali atom stream; an optical waveguide loop having a first port and a second port, wherein the first port is coupled to the second end, wherein the optical waveguide loop has a central axis; a pump laser optically coupled to the input optical waveguide and configured to generate a pump optical signal, wherein the pump optical signal sets the electronic ground state of the alkali atoms in the alkali atom stream; a first optical detector configured to measure the amplitude of light emitted from the alkali atom stream when the pump optical signal is applied to the alkali atom stream; an output optical waveguide having an end coupled to the second port; wherein The input optical waveguide, the optical waveguide loop, and the output optical waveguide each have at least one outer surface, wherein each of the outer surfaces is configured to have a red-blue light evanescent well above the outer surface, wherein the red-blue light evanescent well is configured to transmit a stream of alkali atoms, and wherein the red-blue light evanescent well is formed by a red-detuned optical signal and a blue-detuned optical signal; at least one Bragg laser, the at least one Bragg laser configured to generate at least one field of at least one Bragg light beam, the at least one Bragg light beam comprising a Bragg optical pulse, the Bragg optical pulse configured to split the alkali atoms into two half-wave function streams; wherein the first port, the second port, the second end, and the end of the output optical waveguide are configured to receive at least one at least one field of a Bragg optical beam, the at least one Bragg optical beam comprising a Bragg optical pulse configured to split alkali atoms into two half-wave function streams, wherein a first half-wave function stream travels clockwise around the optical waveguide loop and a second half-wave function stream travels counterclockwise around the optical waveguide loop; wherein the Bragg optical pulse is further configured to recombine the first half-wave function and the second half-wave function into recombined alkali atoms after the first half-wave function and the second half-wave function have each traversed the optical waveguide loop, wherein some of the recombined alkali atoms exit over and along an outer surface of an output optical waveguide and other of the recombined alkali atoms exit over and along an outer surface of an input optical waveguide;and a second optical detector configured to measure the amplitude of light emitted from the stream of recombined alkali atoms exiting above and along the outer surface of the output optical waveguide when a pump optical signal or another optical signal is applied to the stream of recombined alkali atoms exiting above and along the outer surface of the output optical waveguide, wherein the number of recombined alkali atoms exiting above and along the outer surface of the output optical waveguide depends on the rotation rate about the central axis of the optical waveguide loop.;

[0086] Embodiment 14 includes the gyroscope of embodiment 13, further comprising a measurement laser configured to generate another optical signal applied to the flow of recombined alkali atoms over and exiting along an outer surface of the output optical waveguide.

[0087] Embodiment 15 includes the gyroscope of any one of Embodiments 13 to 14, the gyroscope further comprising at least one cooling laser, the at least one cooling laser being configured to generate at least one cooling light beam applied to the alkali atom flow after the alkali atom flow enters the red and blue light evanescent well around the input optical waveguide.

[0088] Embodiment 16 includes the gyroscope of embodiment 15, wherein the at least one cooling beam comprises at least one cooling beam configured to cool the alkali atom stream in one direction or two opposite directions of at least one axis orthogonal to the direction of travel of the alkali atom stream.

[0089] Embodiment 17 comprises the gyroscope of any one of embodiments 15 to embodiment 16, wherein at least one cooling beam comprises two cooling beams, the two cooling beams form a plane with the alkali atom flow, wherein each of the two cooling beams has a vector component parallel to the traveling direction of the alkali atom flow, wherein the component of one cooling beam is in an opposite direction relative to the component of the other cooling beam; and wherein the speed of the alkali atom flow depends on the incident angles of the two cooling beams relative to the alkali atom flow, the frequency difference of the two cooling beams, and the average wavelength of the two cooling beams.

[0090] Embodiment 18 includes the gyroscope of any one of Embodiments 13 to 17, the gyroscope further comprising an optical baffle between the input optical waveguide and the output optical waveguide through the optical waveguide loop.

[0091] Embodiment 19 includes the gyroscope of any one of Embodiments 13 to 18, wherein a first connecting optical waveguide between the second end of the input waveguide and the second port of the optical waveguide loop is parallel to, not in contact with, and adjacent to a second connecting optical waveguide between the end of the output optical waveguide and the first port of the optical waveguide loop, wherein a single red-blue evanescent light trap is above at least one outer surface of the optical waveguides forming both the first connecting optical waveguide and the second connecting optical waveguide.

[0092] Embodiment 20 includes the gyroscope of any one of Embodiments 13 to 19, wherein the grating is coupled to the first end of the input optical waveguide and is configured to emit a divergent field of a red detuned optical signal to attract the alkali atom flow to the red and blue light evanescent well.

[0093] The terms of relative position as used in this application are defined based on a plane parallel to the conventional plane or working surface of a layer or substrate, regardless of the orientation. The terms "horizontal" or "lateral" as used in this application are defined as a plane parallel to the conventional plane or working surface of a layer or substrate, regardless of the orientation. The term "vertical" refers to a direction perpendicular to the horizontal. Terms such as "upper", "side" (as in "sidewall"), "higher", "lower", "above", "top" and "below" are defined relative to a conventional plane or working surface located on the top surface of a layer or substrate, regardless of the orientation.

[0094] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. For example, it should be understood that many different types of lasers may also be used. It is apparent, therefore, that the present invention shall be limited only by the claims and their equivalents.

Claims

1. A device comprising: an input optical waveguide comprising a first end and a second end, wherein the first end is configured to receive a flux of alkali atoms; an optical waveguide loop having a first port and a second port, wherein the first port is coupled to the second end, wherein the optical waveguide loop has a central axis; a first light detector configured to measure an amplitude of light emitted from the alkali atom stream when a pump light signal is applied to the alkali atom stream around the input optical waveguide, wherein the pump light signal sets an electronic ground state of alkali atoms in the alkali atom stream; an output optical waveguide having an end coupled to the second port; wherein the input optical waveguide, the optical waveguide loop, and the output optical waveguide each have at least one outer surface, wherein each of the outer surfaces is configured to have a red-blue light evanescent well above the corresponding outer surface, wherein the red-blue light evanescent well is configured to transmit the alkali atom flow, and wherein the red-blue light evanescent well is formed by a red-detuned optical signal and a blue-detuned optical signal; wherein the first port, the second port, the second end, and the end of the output optical waveguide are configured to receive at least one field of at least one Bragg beam, the at least one Bragg beam comprising Bragg optical pulses configured to split the alkali atoms into two half-wave function streams, wherein a first half-wave function stream travels clockwise around the optical waveguide loop and a second half-wave function stream travels counterclockwise around the optical waveguide loop; wherein the Bragg optical pulse is further configured to recombine the first half-wave function and the second half-wave function into recombined base atoms after the first half-wave function and the second half-wave function have each traversed the optical waveguide loop, wherein some of the recombined base atoms exit above and along an outer surface of the output optical waveguide and other recombined base atoms exit above and along an outer surface of the input optical waveguide; a second optical detector configured to measure an amplitude of light emitted from the flow of the recombinant base atoms exiting above and along the outer surface of the output optical waveguide when the pump optical signal or another optical signal is applied to the flow of the recombinant base atoms exiting above and along the outer surface of the output optical waveguide, wherein the number of recombinant base atoms exiting above and along the outer surface of the output optical waveguide depends on the rotation rate about the central axis of the optical waveguide loop. 2 . The apparatus of claim 1 , wherein the alkali atom flow around the input optical waveguide is configured to receive at least one cooling light beam after entering the red-blue light evanescent trap around the input optical waveguide.

3. The device of claim 1 , wherein a first connecting optical waveguide between the second end of the input optical waveguide and the second port of the optical waveguide loop is parallel to, not in contact with, and adjacent to a second connecting optical waveguide between the end of the output optical waveguide and the first port of the optical waveguide loop, wherein a single red-blue evanescent light trap is above at least one outer surface of optical waveguides forming both the first connecting optical waveguide and the second connecting optical waveguide.

4. The apparatus of claim 1 , wherein the at least one cooling beam comprises at least one cooling beam configured to cool the alkali atom flow in one direction or two opposite directions of at least one axis orthogonal to the direction of travel of the alkali atom flow.

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