Quantum sensor and method for producing same

Abstract

. The invention relates to a quantum sensor, in particular an atom interferometer. The invention also relates to a method for producing a quantum sensor of this type. . . . .

Description

[0001] Quantum sensor and method for its production

[0002] The invention relates to a quantum sensor, in particular an atom interferometer. The invention also relates to a method for producing such a quantum sensor.

[0003] A quantum sensor is a sensor device that can sense physical quantities, such as acceleration, with high precision by utilizing properties of quantum mechanics, such as quantum entanglement, quantum interference, or quantum state squeezing. The quantum sensor can be designed, for example, as an atom interferometer. An atom interferometer is an interferometer that utilizes the wave properties of atoms. Atom interferometers can be used, for example, as accelerometers, rotation sensors, or gravitational gradiometers. An atom interferometer is known, for example, from EP 3 899 990 A1.

[0004] The invention is based on the object of providing a further improved quantum sensor and a method for its production.

[0005] This object is achieved with a quantum sensor according to claim 1. The quantum sensor, which can be designed as an atom interferometer, has the following features:

[0006] - at least one system for holding at least one atom in an atom capture area,

[0007] - at least one optical capture device for capturing the at least one atom in the atom capture region by optical signals, wherein the sensor device has at least one first light source configured to emit light having a first wavelength, - at least one optical sensor device for sensing at least one physical quantity of the at least one atom trapped in the atom capture region, wherein the optical capture device has at least one second light source configured to emit light having a second wavelength,

[0008] - wherein at least one optically functionalized layer is arranged in the light beam path from the first light source (1) and / or the second light source to the system for holding at least one atom, by means of which layer the light emitted by the first and / or second light source is reflected and / or deflected.

[0009] The invention has the advantage that the design and equipment complexity required to implement such a quantum sensor can be significantly reduced compared to known solutions. In particular, it is not necessary to use multiple separate first light sources that emit light from different directions onto the atom capture region to implement the optical capture device, or to generate such light emission using a complex mirror arrangement. The quantum sensor according to the invention can in particular be implemented using an optical capture device that has only a single first light source, e.g., a controllable laser. The light beam characteristics required for the optical capture process of an atom in the atom capture region can then be realized by appropriately designing the optically functionalized layer, which has corresponding reflective and / or light-deflecting characteristics.For example, the first light source can radiate the light onto the optically functionalized layer, where the desired beam characteristic in the atom capture range can then be realized by appropriate reflection and / or light deflection.

[0010] A further advantage of the invention is that the quantum sensor can also be optimized with regard to the arrangement and design of the optical sensor device. In particular, significant miniaturization is possible compared to known solutions. For example, in the quantum sensor according to the invention, the second light source can be arranged such that the light emission direction of the second light source is parallel to and / or overlaps the light emission direction of the first light source. This also enables significant miniaturization.

[0011] Advantageously, due to the previously explained design characteristics, the quantum sensor according to the invention can be manufactured particularly well using microtechnological process steps, e.g., for the production of the at least one optically functionalized layer, which can be applied directly to the system for holding at least one atom. The system for holding at least one atom can, for example, be designed as an atom chip or comprise an atom chip.

[0012] In principle, it is possible for the first wavelength to be the same as the second wavelength. In one advantageous embodiment of the invention, the first wavelength is a different wavelength than the second wavelength. This allows further advantageous effects to be achieved, particularly with a reflective layer with wavelength-specific reflection properties. Furthermore, the first light source can be adjustable with regard to the wavelength of the emitted light, at least within a small wavelength range, in order to temporarily realize a wavelength shift, for example into the blue or red range. For example, the first wavelength can be approximately 780 nm, the second wavelength approximately 795 nm.

[0013] The optical trapping device can be used to cool the individual atoms in the atom trapping area, in particular to temperatures in the microkelvin range.

[0014] The system can additionally have a magnetic capture device for capturing or holding the at least one atom in the atom capture region. The magnetic capture device can be configured, for example, to generate a quadrupole magnetic field in the atom capture region. By energizing the electrical lines of an electromagnet device of the magnetic capture device, the atoms captured by the optical capture device can be held in the atom capture region and thus stored there. Further cooling of the atoms can be achieved, for example, by evaporative cooling.

[0015] The device, in particular the quantum sensor, can also have an atom delivery device, through which the at least one atom to be captured in the atom capture region for measurement purposes is provided. For example, the atom delivery device can be designed as a dispenser. Suitable materials for providing the atoms to be analyzed include alkali metals or rubidium.

[0016] According to an advantageous embodiment of the invention, the at least one optically functionalized layer is arranged between the atom capture region and the system, in particular, it is arranged in the immediate vicinity of the system or is applied to the surface of the system. This allows the effectiveness of the optically functionalized layer to be further optimized. Furthermore, the quantum sensor can be further miniaturized.

[0017] According to an advantageous embodiment of the invention, the at least one optically functionalized layer has at least one optical reflection layer, through which light radiated by the first and / or second light source onto the at least one optically functionalized layer is at least partially reflected. This allows, for example, certain light components of the light radiated onto the at least one optically functionalized layer to be reflected, while other light components can be transmitted, for example, through the optical reflection layer.

[0018] According to an advantageous embodiment of the invention, the at least one optical reflection layer is configured for wavelength-specific reflection of light in such a way that light of the second wavelength is completely or predominantly reflected and light of the first wavelength is completely or predominantly transmitted through the optical reflection layer. This has the advantage that the light emitted by the sensor device cannot essentially penetrate the optical reflection layer but is reflected back, whereas the light from the first light source can pass through the optical reflection layer and in this way, for example, strike an optical deflection layer located behind it. This enables the light from the first light source to reach the atom capture region with a different beam characteristic than the light from the second light source.For example, the at least one optical reflection layer can be constructed like a Bragg mirror. Such a Bragg mirror can be realized from alternating thin layers with different refractive indices. In an advantageous embodiment, the layers can consist of dielectrics.

[0019] According to an advantageous embodiment of the invention, the at least one optically functionalized layer has at least one optical deflection layer, by means of which light irradiated from the first and / or second light source onto the at least one optically functionalized layer is deflected at a reflection angle that differs from the incidence angle, in particular is deflected in the direction of the atom capture region. This has the advantage that the light reaching the optical deflection layer can be deflected at a desired reflection angle, e.g. back towards the atom capture region. The at least one deflection layer can, for example, have at least one optical grating in which the optical deflection occurs by diffraction at the grating. The at least one optical deflection layer can also contain other types of optical deflection, e.g. an arrangement of a plurality of micromirrors and / or microprisms.

[0020] In an advantageous embodiment, the at least one optically functionalized layer or at least the deflection layer can be designed as a passive, non-controllable layer. This further reduces the effort required to implement the quantum sensor and further improves the possibilities for miniaturization.

[0021] Reflection, within the meaning of the present application, is considered in particular a characteristic of the optical reflection layer in which light irradiated orthogonally onto the optical reflection layer is in turn reflected back orthogonally and thus parallel to the incident light. Optical deflection, within the meaning of the present application, is understood in particular to mean a property of the optical deflection layer by which it deflects light irradiated orthogonally onto the optical deflection layer in a direction deviating from the orthogonal direction. The light irradiated orthogonally onto the optical deflection layer is thus deflected at a reflection angle that is not parallel to the incident angle.

[0022] According to an advantageous embodiment of the invention, the at least one optical deflection layer is arranged behind the at least one optical reflection layer, as seen from the first and / or second light source. This has the advantage that only that portion of the light from the first and second light sources that can pass through the optical reflection layer reaches the optical deflection layer.

[0023] According to an advantageous embodiment of the invention, the at least one optical deflection layer is divided into a plurality of subsections, e.g., into at least three subsections, each subsection having a different deflection direction of the incident light than the other subsections. As a result, a complex light-guiding characteristic can be realized with little effort and, in particular, with a very small installation size, by means of which, in particular, a capture of the at least one atom in the atom capture region can be realized in three spatial dimensions. In particular, the at least one optical deflection layer with its subsections can be designed such that the light from all subsections is deflected in the direction of the atom capture region. The plurality of subsections of the deflection layer can be arranged next to one another on the same plane, or they can be arranged in planes that are slightly offset from one another.

[0024] According to an advantageous embodiment of the invention, the at least one optical deflection layer is planarized by means of a planarization layer, at least on the side facing the at least one optical reflection layer. This has the advantage that if the optical deflection layer is implemented with surface irregularities, these can be compensated for by means of the planarization layer. In particular, if the deflection layer is implemented with an optical grating, the irregularities of the grating structures can be compensated for. Accordingly, the optical reflection layer arranged on the optical deflection layer can also be implemented as a flat, smooth layer. For example, a thin layer of spin-on-glass (SoG) can be applied to the optical deflection layer as a planarization layer, e.g. with a layer thickness of a maximum of 10 pm, in particular a maximum of 5 pm or a maximum of 1 pm.

[0025] According to an advantageous embodiment of the invention, the at least one optical deflection layer is arranged on a substrate or has a substrate, wherein electrical conductor tracks are integrated into the substrate. In this way, the overall structure of the quantum sensor can be made even more compact. For example, the electrical conductor tracks arranged in the substrate can be used as parts of an electromagnet device for generating a magnetic field of a magnetic capture device of the quantum sensor.

[0026] According to an advantageous embodiment of the invention, the light emission direction of the first light source is aligned parallel and / or overlapping with the light emission direction of the second light source. This allows the design of the quantum sensor to be further miniaturized.

[0027] According to an advantageous embodiment of the invention, at least the at least one optically functionalized layer is designed as a microtechnological layer. This also allows further miniaturization of the quantum sensor. The microtechnological layers can be applied using known microtechnological processes, in particular conventional CVD and PVD processes. For example, the at least one reflection layer can have a maximum thickness of 20 pm or a maximum of 10 pm. The at least one optical deflection layer can have a maximum thickness of 20 pm or a maximum of 10 pm. In particular, the thickness of the optical deflection layer, if it is designed as a grating structure of an optical grating, can have a maximum thickness of 200 nm. Added to this is the thickness of a substrate layer on which such a maximum 200 nm thick layer of the optical grating can be applied.

[0028] The object stated above is also achieved by a method for producing a quantum sensor of the type explained above, in which the at least one optically functionalized layer is applied to the system for holding at least one atom by means of microtechnological processes. This allows very efficient production of a quantum sensor with the advantageous properties explained above, in particular a highly miniaturized quantum sensor. For example, the system can first be provided as a component, and the sublayers of the at least one optically functionalized layer can then be applied to this, e.g. first the optical deflection layer and then the optical reflection layer. Furthermore, the aforementioned planarization layer can be applied to the optical deflection layer before the optical reflection layer is applied.

[0029] The invention is explained in more detail below using exemplary embodiments and drawings.

[0030] It shows

[0031] Figure 1 shows a quantum sensor in a side sectional view,

[0032] Figure 2 shows an embodiment of an optically functionalized layer of the quantum sensor in a perspective view,

[0033] Figure 3 shows a possible embodiment of a magnetic capture device of the quantum sensor.

[0034] Figure 1 shows a quantum sensor having a system 5 for holding at least one atom 13 in an atom capture region 4. The quantum sensor further comprises an optical capture device 12 for capturing the at least one atom 13 in the atom capture region 4 using optical signals from a first light source 1 of the optical capture device 12. The first light source 1 is configured to emit light 14 having a first wavelength. The quantum sensor further comprises an optical sensor device 11 for sensing at least one physical quantity of the at least one atom 13 trapped in the atom capture region 4. For this purpose, the optical sensor device 11 has a second light source 2 configured to emit light 15 having a second wavelength.

[0035] To carry out measurements on the atom 13, the sensor device 11 has, for example, a measuring device 3, e.g. an optical interferometer.

[0036] In the light beam path of the light 14 from the first light source 1 and / or the light 15 from the second light source 2 to the system 5, the quantum sensor has at least one optically functionalized layer 7. The optically functionalized layer 7 has an optical deflection layer 10, which can be applied to the system 5 either directly or via at least one intermediate layer. Since the optical deflection layer 10 can be relatively thin, particularly when designed as a grating, the optical deflection layer 10 can be applied to a substrate 19.

[0037] An optical reflection layer 8 is applied to the optical deflection layer 10. To flatten any unevenness on the surface of the optical deflection layer 10 facing the optical reflection layer 8, a planarization layer 9 can be arranged on the optical deflection layer 10. The optical reflection layer 8 is then applied to this planarization layer. The quantum sensor can furthermore have a magnetic trapping device 6 with a magnetic field generating device to additionally hold the atoms 13 trapped in the atom trapping region 4 there using magnetic fields.

[0038] It can be seen that the light 15 emitted by the second light source 2, which strikes the optical reflection layer 8, is essentially completely reflected as reflected light 16. In contrast, the optical reflection layer 8 is transparent to the light 14 from the first light source 1, so that this light strikes the optical deflection layer 10, where it is deflected and scattered in other directions as light rays 17, e.g., by diffraction at the grating.

[0039] Using such an optically functionalized layer, a miniaturized optical trapping device 12 can be realized, for example, for an atom interferometer, in which trapping of the atoms 13 in the atom trapping region 4 can occur in all three spatial dimensions. This is explained by way of example with reference to Figure 2. In the embodiment of Figure 2, the optical deflection layer 10 is divided into three subsections 18. The subsections 18 each have different deflection directions, so that the light beams 14 of the first light source 1 impinging on the optical deflection layer 10 are deflected and scattered in different directions, so that a substantial portion of the scattered light 17 from all subsections 18 meets in the atom trapping region 4.By appropriate light emission of the light rays 14 and a corresponding slight variation of the wavelength of the light 14, the atom 13 can be held in a certain position by light 14 and light 17 striking the atom 13.

[0040] Figure 3 shows an advantageous structure of the magnetic capture device 6 in combination with the system 5 and the optically more functional layer 7. For example, the system 5 can be constructed from several individual parts or layers. The magnetic capture device 6 can have mesoscopic structures for generating a quadrupole magnetic field in the atom capture region 4.

[0041] As mentioned, electrical conductor tracks can be integrated into the substrate 19. For this purpose, depressions can first be etched into the substrate during production of the substrate 19. Depending on the substrate material, an electrical insulation layer is applied, followed by adhesion promoter layers and electrical starter layers, before the depression is electroplated. Due to the geometry of the depression, excessive electrical field elevations can occur in the area of ​​the edges during electroplating. The result is overgrowth in these areas, which leads to the formation of "edge ridges". Chemical mechanical polishing (CMP), for example, can be used for planarization as a common process in microtechnology.Since the adhesion of layers to the system's gold / copper conductors is not optimal, it is possible to coat the top surface of the conductors with an appropriately structured adhesion promoter layer. This layer is applied only to the conductors themselves and not to other areas of the substrate, as this would otherwise cause short circuits. This layer is followed by another layer of SiO2, which forms the basis for the subsequent optically functionalized layer 7 and also serves as an electrical insulator. Alternatively, an Al2O3 layer can also be used.

[0042] For the production of the optical deflection layer 10, e.g. in the form of an optical grating, at least three processes are available depending on the design requirements:

[0043] 1. The material for the grating is deposited over the entire surface, with a layer thickness at least equal to the height of the grating. This is followed by structuring using lithography and etching techniques. 2. The material for the grating is deposited over the entire surface. A photoresist is then applied and structured. In the next step, the material for the grating is again deposited over the entire surface and structured using lift-off of the photoresist.

[0044] 3. The SiO2 top layer (alternatively: other top layer) of the system is patterned directly (see point 1). The actual grid material is then applied as a top layer to the pre-patterned structure.

[0045] Optical coatings without gratings can be deposited directly on the top layer of the system.

[0046] Optical coatings on optical gratings initially require a flat surface, which requires the gaps between the optical gratings to be "filled in." One advantageous approach is to apply a thin layer of spin-on-glass (SoG) up to 1 μm thick (the pits of the gratings are in the low three-digit nm range). The SoG partially compensates for the pits, and a CMP step is also used to achieve final planarization. The optical coating is then applied to this layer as described above.

[0047] *****

Claims

Patent claims:

1. Quantum sensor, in particular atom interferometer, with - at least one system (5) for holding at least one atom (13) in an atom capture region (4), - at least one optical capture device (12) for capturing the at least one atom (13) in the atom capture region (4) by means of optical signals, wherein the sensor device (11) has at least one first light source (1) which is arranged to emit light (14) having a first wavelength, - at least one optical sensor device (11) for sensing at least one physical quantity of the at least one atom (13) trapped in the atom trapping region (4), wherein the optical trapping device (12) has at least one second light source (2) which is designed to emit light (15) with a second wavelength, - wherein at least one optically functionalized layer (7) is arranged in the light beam path from the first light source (1) and / or the second light source (2) to the system (5), by means of which layer the light (14, 15) emitted by the first and / or second light source (1, 2) is reflected and / or deflected.

2. Quantum sensor according to claim 1, characterized in that the at least one optically functionalized layer (7) is arranged between the atom capture region (4) and the system (5), in particular is arranged in the immediate vicinity of the system (5) or is applied to the surface of the system (5).

3. Quantum sensor according to one of the preceding claims, characterized in that the at least one optically functionalized layer (7) has at least one optical reflection layer (8) by which light radiated from the first and / or second light source (1, 2) onto the at least one optically functionalized layer (7) is at least partially reflected.

4. Quantum sensor according to claim 3, characterized in that the at least one optical reflection layer (8) is configured for wavelength-specific reflection of light such that light of the second wavelength is completely or predominantly reflected and light of the first wavelength is completely or predominantly transmitted through the optical reflection layer (8).

5. Quantum sensor according to one of the preceding claims, characterized in that the at least one optically functionalized layer (7) has at least one optical deflection layer (10) by which light radiated from the first and / or second light source (1, 2) onto the at least one optically functionalized layer (7) is deflected at a reflection angle deviating from the angle of incidence, in particular is deflected in the direction of the atom capture region (4).

6. Quantum sensor according to claim 5, characterized in that the at least one optical deflection layer (10) is arranged behind the at least one optical reflection layer (8) as seen from the first and / or second light source (1, 2).

7. Quantum sensor according to one of claims 5 to 6, characterized in that the at least one optical deflection layer (10) is divided into several subsections (18), wherein each subsection (18) has a different deflection direction of the incident light than the other subsections (18).

8. Quantum sensor according to one of claims 5 to 7, characterized in that the at least one optical deflection layer (10) is planarized by means of a planarization layer (9) at least on the side facing the at least one optical reflection layer (8).

9. Quantum sensor according to one of claims 5 to 8, characterized in that the at least one optical deflection layer (10) is arranged on a substrate (19) or has a substrate (19), wherein electrical conductor tracks are integrated in the substrate (19).

10. Quantum sensor according to one of the preceding claims, characterized in that the light emission direction of the first light source (1) is aligned parallel and / or overlapping to the light emission direction of the second light source (2).

11. Quantum sensor according to one of the preceding claims, characterized in that at least the at least one optically functionalized layer (7) is designed as a microtechnological layer.

12. Quantum sensor according to one of the preceding claims, characterized in that the system (5) comprises an atom chip or is designed as such.

13. A method for producing a quantum sensor according to one of the preceding claims, characterized in that the at least one optically functionalized layer (7) is applied to the system (5) by means of microtechnological methods.

Images