A continuous room-temperature microwave maser method and device based on a rydberg atom gas cell

Abstract

The application discloses a continuous room-temperature microwave maser method and device based on a Rydberg atom gas chamber, wherein the device comprises a rectangular alkali metal atom gas chamber, an open microwave cavity, a one-dimensional vertical lifting platform, a laser, a coaxial converter, a radio frequency cable, a low-noise amplifier and a spectrum analyzer; the application utilizes the long lifetime of the Rydberg atom and the naturally satisfied particle number inversion, tunes the resonance frequency of the open microwave cavity to the resonance frequency of the Rydberg atom pulse transition frequency, generates a continuous pulse signal of the Rydberg atom under the action of the open microwave cavity, finally amplifies the pulse signal through the low-noise amplifier, and realizes the continuous room-temperature pulse emission device based on the Rydberg atom gas chamber through the misplacement pumping of the Rydberg atom.

Description

Technical Field

[0001] This invention relates to the field of quantum sensing and quantum precision measurement, specifically to a continuous room temperature microwave maser method and apparatus based on a Rydberg atomic gas cell. Background Technology

[0002] Maser, short for Microwave Amplification by Stimulated Emission of Radiation, is a quantum device that uses the resonant interaction between electromagnetic waves in the microwave band and quantum systems such as atoms or molecules to obtain amplified signals or oscillations in the microwave band.

[0003] As a precursor to optical lasers, masers have long been limited in their application in many scenarios due to their reliance on cryogenic cooling and high-vacuum systems. However, their potential superior performance as low-noise amplifiers holds great promise for applications in deep-space communication and radio astronomy. Previously, research teams have utilized the organic molecule pentacene-doped p-terphenyl to achieve room-temperature pulsed masers and optically pumped diamond NV centers to achieve room-temperature continuously excited solid-state masers. However, the heat dissipation performance of p-terphenyl-doped p-terphenyl only allows for the observation of short-duration pulsed masers, while optically pumped diamond NV center systems require a strong magnetic field to achieve population inversion.

[0004] Here, we propose a method and apparatus for achieving continuous room-temperature maser based on a Rydberg atom gas cell. By utilizing the long lifetime of Rydberg atoms and the naturally satisfied population inversion condition, and through the design of an atomic gas cell and an open microwave cavity, misaligned pumping of Rydberg atoms is achieved, enabling continuous microwave maser operation at room temperature without a high vacuum system and a strong magnetic field. Summary of the Invention

[0005] In view of this, the present invention proposes a continuous room temperature microwave maser method and device based on a Rydberg atomic gas cell, which has a simple structure, does not require a cryogenic refrigeration system and a high vacuum system, and is highly feasible.

[0006] To achieve the above-mentioned objectives, this application proposes a continuous room temperature microwave maser based on a Rydberg atomic gas cell, comprising a rectangular alkali metal atomic gas cell, an open microwave cavity, a one-dimensional vertical lifting platform, and a laser.

[0007] A circular coupling hole is provided at the bottom center of the open microwave cavity, and the rectangular alkali metal atom gas chamber is placed directly above the circular coupling hole;

[0008] The one-dimensional vertical lifting platform is connected to the bottom of the open microwave cavity and is used to tune the resonant frequency of the open microwave cavity.

[0009] The standing wave field inside the open microwave cavity coincides with the square alkali metal atom gas cell.

[0010] The laser is used to emit probe light and coupling light to excite the atoms in the square alkali metal atom gas cell to the Rydberg state and realize continuous room temperature microwave lasing of Rydberg atoms to generate a maser signal.

[0011] Furthermore, the device also includes an axis converter, an RF cable, a low-noise amplifier, and a spectrum analyzer;

[0012] The coaxial converter is connected to the open microwave cavity, couples the pulsator signal into the radio frequency cable, amplifies it through the low-noise amplifier, and then transmits it to the spectrum analyzer through another radio frequency cable.

[0013] Furthermore, the open microwave cavity is composed of a hemispherical mirror and a plane mirror. The circular coupling hole is located on the plane mirror. The hemispherical mirror is fixed directly above the plane mirror. The plane mirror is connected to the one-dimensional vertical lifting platform. The hemispherical mirror and the plane mirror are made of copper and have silver plating on their surfaces.

[0014] Furthermore, the rectangular alkali metal atom gas chamber is made of quartz and is filled with alkali metal atom gas. The atoms in the rectangular alkali metal atom gas chamber can move thermally within the space of two antinodes and one node of the open microwave cavity.

[0015] Furthermore, the major axis of the coaxial converter is parallel to the major axis of the rectangular alkali metal atom gas chamber to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is the same as the polarization direction of the electromagnetic field in the coaxial converter.

[0016] Furthermore, the device also includes a circulator, which includes an input terminal, an output terminal, and an isolation terminal. The isolation terminal is connected to the coaxial converter, the input terminal is used to receive external signals, and the output terminal is connected to the radio frequency cable.

[0017] On the other hand, this application also proposes a continuous room temperature microwave maser method based on a Rydberg atomic gas cell, comprising the following steps:

[0018] Step 301: Place the rectangular alkali metal atom gas cell into the open microwave cavity and position it directly above the circular coupling hole;

[0019] Step 302: The probe light and the coupling light are directed into the rectangular alkali metal atom chamber in opposite directions. The position where the probe light and the coupling light coincide is at the node of the standing wave formed by the open microwave cavity, which excites the Rydberg atoms.

[0020] Step 303: Adjust the one-dimensional vertical lifting platform so that the resonant cavity frequency of the open microwave cavity resonates with the frequency of the Rydberg atom maser transition, thereby causing the Rydberg atoms excited at the nodes of the standing wave field to fly to the antinodes of the standing wave field under thermal motion and generate maser signals.

[0021] Further, step 301 specifically includes:

[0022] A hemispherical mirror of the open microwave cavity is fixed, and a plane mirror is connected to a one-dimensional vertical lifting platform. A coaxial converter is placed and fixed under the circular coupling hole of the plane mirror to couple the electromagnetic field in the open microwave cavity. A rectangular alkali metal atom gas cell is placed on the circular coupling hole of the plane mirror of the open microwave cavity, and the long axis of the gas cell needs to be parallel to the long axis of the coaxial converter to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is consistent with the polarization direction in the coaxial converter.

[0023] Further, step 302 specifically includes:

[0024] By using optical fibers, the probe light and coupling light generated by two tunable lasers enter from both ends of a rectangular alkali metal atom gas cell. The probe light and coupling light coincide with the atomic clusters at their nodes in the open microwave cavity. Under the combined action of the probe light and coupling light, misalignment pumping is achieved, exciting the atoms to the Rydberg state and producing an observable electromagnetically induced transparency phenomenon.

[0025] Furthermore, step 303 specifically includes:

[0026] After observing the electromagnetically induced transparency phenomenon, the cavity length of the open microwave cavity was tuned by adjusting the height of the one-dimensional vertical translation stage, so that the resonant frequency of the microwave cavity resonated with the maser transition frequency of the atoms. This allowed Rydberg atoms, which were displaced and pumped at the nodes, to fly to the antinodes of the standing wave through thermal motion, strongly couple with the microwave mode at the antinodes, and generate maser signals, thus producing continuous maser signals of displaced pumped Rydberg atoms.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0028] 1. This invention is based on a continuous room temperature microwave maser method using a Rydberg atom gas cell. It combines the population inversion condition naturally satisfied by Rydberg atoms to achieve population inversion without the need for an external strong magnetic field, and does not require a complex cryogenic refrigeration system or a high vacuum system.

[0029] 2. The present invention is a continuous room temperature microwave lasing device based on a Rydberg atom gas cell. By using misaligned pumping, the preparation of Rydberg atoms and the emission of Rydberg masers are spatially misaligned, and the emission of Rydberg masers does not affect the preparation of Rydberg atoms, thereby achieving continuous emission of Rydberg masers.

[0030] 3. The present invention is a continuous room temperature microwave maser device based on a Rydberg atomic gas cell. By tuning the resonant cavity frequency of the open microwave cavity, it can resonate with the Rydberg maser emission frequencies of different frequencies, thereby realizing continuous Rydberg maser emission at different frequencies. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the continuous room temperature microwave maser based on the Rydberg atomic gas chamber of the present invention.

[0033] Figure 2 This is a schematic diagram of the energy level structure of the continuous room temperature microwave lasing process based on the Rydberg atomic gas cell according to the present invention.

[0034] Figure 3 This is a schematic diagram of the device for amplifying weak signals based on continuous room temperature microwave lasing in a Rydberg atomic gas cell according to the present invention.

[0035] Figure 4 This is a flowchart of the continuous room temperature microwave lasing method based on the Rydberg atomic gas cell of the present invention.

[0036] Figure 5 This is a flowchart illustrating the weak signal amplification achieved by continuous room-temperature pulsation based on a Rydberg atomic gas cell, according to the present invention. Detailed Implementation

[0037] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1As shown, the present invention provides a continuous room temperature microwave maser based on a Rydberg atomic gas cell, including a rectangular alkali metal atomic gas cell 1, an open microwave cavity plane mirror 3, an open microwave cavity hemispherical mirror 4, a circular coupling hole 5, a coaxial converter 8, an RF cable 9, a low noise amplifier 10, a spectrum analyzer 11, and a one-dimensional vertical lifting platform 12.

[0039] Figure 2 The diagram shows the energy level structure of atoms generating Rydberg maser signals within a rectangular alkali metal atom gas cell 1. Taking rubidium-87 atoms as an example, 201(5S) 1 / 2 ,F=2,mF=2) represents the ground state of a rubidium atom, 202(5P) 3 / 2 F = 3) represents the intermediate excited state of a rubidium atom, 203(63D) 5 / 2 ) and 204 (64P) 3 / 2 209 represents the two Rydberg states of a rubidium atom; 210 represents the probe light with a wavelength of 780 nm; 211 represents the coupling light with the Rydberg state 63D. 5 / 2 →64P 3 / 2 Microwave pulsator signal with a frequency of 8.365481 GHz, exhibiting inter-transition resonance. 205 (5S) 1 / 2 (F = 2, mF = 1) represents the ground state of a rubidium atom, 206(5P) 3 / 2 ,F=2) represents the intermediate excited state of a rubidium atom, 201(5S 1 / 2 (F=2, mF=2) represents the ground state of a rubidium atom, and 207 is the pump-back light with a wavelength of 795 nm. 208 represents the light that falls to 201 (5S). 1 / 2 Photons of light waves (F = 2, mF = 2).

[0040] When probe light 209 and coupling light 210 are incident on the rectangular alkali metal atom gas cell 1 in opposite directions, an electromagnetically induced transparent window is formed. At this time, increasing the power of probe light 209 and the coupling light 202(5P)... 3 / 2 The detuning of F=3 was measured, and the electromagnetically induced transparent window was observed to transform into an electromagnetically induced absorption window. This was achieved by tuning the resonant cavity frequency of the open microwave cavity, and then adjusting the frequency relative to 203(63D). 5 / 2 ) and 204 (63P) 3 / 2 The 211 transition resonance between ) has a frequency of 8.365481 GHz. In 203(63D) 5 / 2 Rydberg atoms on the surface of the microwave cavity are located at nodes of the standing wave field within the open microwave cavity. Within the coherence time range, the Rydberg atoms at the nodes fly out of the standing wave nodes and into the antinodes of the standing wave through thermal motion. Under the mutual resonance with the open microwave cavity, they undergo Rydberg states 63D. 5 / 2 →64P 3 / 2 The transition occurs, generating the Reedberg pulsator signal.

[0041] Specifically, the open microwave cavity plane mirror 3 is connected to the one-dimensional vertical lifting platform 12, and the open microwave cavity hemispherical mirror 4 is fixed directly above the open microwave cavity plane mirror 3. The resonant frequency of the open microwave cavity can be tuned by the one-dimensional vertical lifting platform 12. The rectangular alkali metal atom gas chamber 1 is placed on the open microwave cavity plane mirror 3, and both it and the circular coupling hole 5 on the open microwave cavity plane mirror are at the center. The long axis of the rectangular alkali metal atom gas chamber 1 needs to be parallel to the long axis of the coaxial converter 8 to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is consistent with the polarization direction in the coaxial converter 8. Under the action of the pump back light 207, the probe light 209 and the coupling light 210, the atoms are excited to the Rydberg state. The pump back light 207, the probe light 209 and the coupling light 210 overlap with each other. The probe light 209 and the coupling light 210 overlap in opposite directions in the rectangular alkali metal atom gas chamber 1. The pump back light 207 and the coupling light 210 overlap in the same direction and are located at the nodes of the standing wave field in the open microwave cavity, realizing the misaligned pumping of the Rydberg atoms. By adjusting the distance between the open microwave cavity plane mirror 3 and the open microwave cavity hemispherical mirror 4, the cavity frequency of the open microwave cavity resonates with the Rydberg maser transition signal 211. Rydberg atoms excited at the nodes in the open microwave cavity fly to the antinodes of the standing wave field in the cavity under thermal motion, realizing the misaligned pumped continuous maser signal 211 of Rydberg atoms. The maser signal 211 is coupled out from the open microwave cavity through the coaxial converter 8, and after passing through the radio frequency cable 9 and being amplified by the low noise amplifier 10, it is connected to the spectrum analyzer 11 to obtain the frequency and power of the maser signal 211, thus realizing continuous room temperature maser based on the Rydberg atom gas cell.

[0042] like Figure 3 As shown, the present invention also provides a device for amplifying weak signals by continuous room temperature microwave lasing based on a Rydberg atomic gas cell. Based on the above-mentioned continuous room temperature microwave lasing device based on a Rydberg atomic gas cell, a circulator 6 is added. The isolation port of the circulator 6 is connected to the coaxial converter 8. The input port of the circulator 6 receives weak signals, and the output port of the circulator 6 is connected to the spectrum analyzer 12 via an RF cable 9.

[0043] like Figure 4 As shown, this invention also proposes a continuous room-temperature microwave lasing method based on a Rydberg atomic gas cell, comprising the following steps:

[0044] Step 301: Place the rectangular alkali metal atom gas cell into the open microwave cavity and position it directly above the circular coupling hole;

[0045] Step 302: The probe light and the coupling light are directed into the rectangular alkali metal atom chamber in opposite directions. The position where the probe light and the coupling light coincide is at the node of the standing wave formed by the open microwave cavity, which excites the Rydberg atoms.

[0046] Step 303: Adjust the one-dimensional vertical lifting platform so that the resonant cavity frequency of the open microwave cavity resonates with the frequency of the Rydberg atom maser transition, thereby causing the Rydberg atoms excited at the nodes of the standing wave field to fly to the antinodes of the standing wave field under thermal motion and generate maser signals.

[0047] In step 301, the hemispherical mirror of the open microwave cavity is fixed, the plane mirror is connected to the one-dimensional vertical lifting platform, and a coaxial converter is fixed under the circular coupling hole of the plane mirror for coupling the electromagnetic field in the open microwave cavity. The rectangular alkali metal atom gas cell is placed on the circular coupling hole of the plane mirror of the open microwave cavity, and the long axis of the gas cell needs to be parallel to the long axis of the coaxial converter to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is consistent with the polarization direction in the coaxial converter.

[0048] Specifically, step 302 includes: using optical fibers to allow the probe light and coupling light generated by two tunable lasers to enter from both ends of a rectangular alkali metal atom gas cell. The probe light and coupling light coincide with the atomic clusters at their nodes in the open microwave cavity. Under the combined action of the probe light and coupling light, misalignment pumping is achieved, exciting the atoms to the Rydberg state and producing an observable electromagnetically induced transparency phenomenon.

[0049] Step 303 specifically includes:

[0050] After observing the electromagnetically induced transparency phenomenon, the cavity length of the open microwave cavity was tuned by adjusting the height of the one-dimensional vertical translation stage, so that the resonant frequency of the microwave cavity resonated with the maser transition frequency of the atoms. This allowed Rydberg atoms, which were displaced and pumped at the nodes, to fly to the antinodes of the standing wave through thermal motion, strongly couple with the microwave mode at the antinodes, and generate maser signals, thus producing continuous maser signals of displaced pumped Rydberg atoms.

[0051] like Figure 5 As shown, based on the above-mentioned continuous room temperature microwave lasing method using a Rydberg atomic gas cell, this invention also provides a method for amplifying weak signals using continuous room temperature microwave lasing using a Rydberg atomic gas cell, comprising the following steps:

[0052] Step 401: The probe light and the coupling light are reversed and superimposed to be injected into the rectangular alkali metal atom gas chamber 1 to excite the atoms at the nodes of the standing wave field of the open microwave cavity to the Rydberg state.

[0053] Step 402: Connect the isolation port of circulator 6 to coaxial converter 8. The input port of circulator 6 receives a weak signal, and the output port of circulator 6 is connected to spectrum analyzer 12 via RF cable 9.

[0054] Step 403: The weak signal received at the input port of circulator 6 enters the open microwave cavity through coaxial converter 8. Under the Rydberg atomic maser process in the cavity, the signal is amplified with low noise and then amplified after passing through the output port of circulator 6.

[0055] This invention relates to a method for amplifying weak signals using continuous room-temperature maser based on a Rydberg atomic gas cell. The working principle involves using optical fibers to guide probe light 209 and coupling light 210 generated by two tunable lasers from opposite ends of a rectangular alkali metal atomic gas cell 1 within an open microwave cavity. The probe light 209 and coupling light 210 overlap inside the rectangular alkali metal atomic gas cell 1 and are located at nodes of the standing wave field within the open microwave cavity. Under the combined action of the single-photon and two-photon resonant probe light 209 and coupling light 210, an electromagnetically induced transparent window is formed, realizing Rydberg atom dislocation pumping in the Rydberg maser process. The circulator 6 is connected to an isolation port of a coaxial converter 8, which is then connected to an open microwave cavity plane mirror 3, coupling with the electromagnetic field within the open microwave cavity. The input port of circulator 6 receives microwave signals, which are coupled into the open microwave cavity through coaxial converter 8. Under the continuous pulsation process of Rydberg atoms in the cavity, the signal is amplified with low noise. The amplified signal is output through the output port of circulator 6 and received by spectrum analyzer 12, so that the power and frequency of the amplified signal can be obtained.

[0056] In summary, the continuous room-temperature microwave maser method and apparatus based on Rydberg atom gas cells of the present invention, combined with microwave radio frequency technology, realizes continuous maser emission of Rydberg atoms without the need for cryogenic cooling systems and high vacuum systems, greatly expanding the practical application scenarios of Rydberg atom masers. It can achieve continuous maser emission through misaligned pumped Rydberg atoms, and can also achieve low-noise amplification of weak signals through continuous maser emission of Rydberg atoms. Compared with other maser generators that require cryogenic cooling systems and high vacuum systems, the continuous room-temperature maser apparatus based on Rydberg atom gas cells is more convenient for practical applications and has broad application prospects and scientific research value.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A continuous room-temperature microwave maser based on a Rydberg atomic gas cell, characterized in that, It includes a rectangular alkali metal atom gas chamber, an open microwave cavity, a one-dimensional vertical lifting platform, and a laser; A circular coupling hole is provided at the bottom center of the open microwave cavity, and the rectangular alkali metal atom gas chamber is placed directly above the circular coupling hole; The one-dimensional vertical lifting platform is connected to the bottom of the open microwave cavity and is used to tune the resonant frequency of the open microwave cavity. The standing wave field inside the open microwave cavity coincides with the rectangular alkali metal atom gas chamber. The laser is used to emit probe light and coupling light to excite the atoms in the rectangular alkali metal atom gas chamber to the Rydberg state and realize continuous room temperature microwave lasing of Rydberg atoms to generate a maser signal.

2. The apparatus according to claim 1, characterized in that, It also includes coaxial converters, RF cables, low-noise amplifiers, and spectrum analyzers; The coaxial converter is connected to the open microwave cavity, couples the pulsator signal into the radio frequency cable, amplifies it through the low-noise amplifier, and then transmits it to the spectrum analyzer through another radio frequency cable.

3. The apparatus according to claim 1, characterized in that, The open microwave cavity is composed of a hemispherical mirror and a plane mirror. The circular coupling hole is located on the plane mirror. The hemispherical mirror is fixed directly above the plane mirror. The plane mirror is connected to the one-dimensional vertical lifting platform. The hemispherical mirror and the plane mirror are made of copper and have silver plating on their surfaces.

4. The apparatus according to claim 1, characterized in that, The rectangular alkali metal atom gas chamber is made of quartz and is filled with alkali metal atom gas. The atoms in the rectangular alkali metal atom gas chamber can move thermally within the space of two antinodes and one node of the open microwave cavity.

5. The apparatus according to claim 2, characterized in that, The major axis of the coaxial converter is parallel to the major axis of the rectangular alkali metal atom gas chamber to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is the same as the polarization direction of the electromagnetic field in the coaxial converter.

6. The apparatus according to claim 5, characterized in that, It also includes a circulator, which has an input terminal, an output terminal and an isolation terminal. The isolation terminal is connected to the coaxial converter, the input terminal is used to receive external signals, and the output terminal is connected to the radio frequency cable.

7. A continuous room-temperature microwave lasing method based on a Rydberg atomic gas cell, characterized in that, Includes the following steps: Step 301: Place the rectangular alkali metal atom gas cell into the open microwave cavity and position it directly above the circular coupling hole; Step 302: The probe light and the coupling light are directed into the rectangular alkali metal atom chamber in opposite directions. The position where the probe light and the coupling light coincide is at the node of the standing wave formed by the open microwave cavity, which excites the Rydberg atoms. Step 303: Adjust the one-dimensional vertical lifting platform so that the resonant cavity frequency of the open microwave cavity resonates with the frequency of the Rydberg atom maser transition, thereby causing the Rydberg atoms excited at the nodes of the standing wave field to fly to the antinodes of the standing wave field under thermal motion and generate maser signals.

8. The method according to claim 7, characterized in that, Step 301 specifically includes: A hemispherical mirror of the open microwave cavity is fixed, and a plane mirror is connected to a one-dimensional vertical lifting platform. A coaxial converter is placed and fixed under the circular coupling hole of the plane mirror to couple the electromagnetic field in the open microwave cavity. A rectangular alkali metal atom gas cell is placed on the circular coupling hole of the plane mirror of the open microwave cavity, and the long axis of the gas cell needs to be parallel to the long axis of the coaxial converter to ensure that the polarization direction of the electromagnetic field in the open microwave cavity is consistent with the polarization direction in the coaxial converter.

9. The method according to claim 7, characterized in that, Step 302 specifically includes: By using optical fibers, the probe light and coupling light generated by two tunable lasers enter from both ends of a rectangular alkali metal atom gas cell. The probe light and coupling light coincide with the atomic clusters at their nodes in the open microwave cavity. Under the combined action of the probe light and coupling light, misalignment pumping is achieved, exciting the atoms to the Rydberg state and producing an observable electromagnetically induced transparency phenomenon.

10. The method according to claim 7, characterized in that, Step 303 specifically includes: After observing the electromagnetically induced transparency phenomenon, the cavity length of the open microwave cavity was tuned by adjusting the height of the one-dimensional vertical translation stage, so that the resonant frequency of the microwave cavity resonated with the maser transition frequency of the atoms. This allowed Rydberg atoms, which were displaced and pumped at the nodes, to fly to the antinodes of the standing wave through thermal motion, strongly couple with the microwave mode at the antinodes, and generate maser signals, thus producing continuous maser signals of displaced pumped Rydberg atoms.

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