CN102147538A - Quantum coherence inducted optical rotation effect based atomic filtering method and device - Google Patents
Quantum coherence inducted optical rotation effect based atomic filtering method and device Download PDFInfo
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Abstract
The invention discloses a quantum coherence inducted optical rotation effect based atomic filtering method and device. The method comprises the steps of: (a) irradiating an atomic pool with coupled laser; (b) carrying out crossed beam combining on signal light and the coupled laser in the atomic pool;(c) enabling combined light beams to interact with atomic media to cause the polarization plane of the signal light to rotate; (d) carrying out beam splitting on the coupled laser and the signal light and irradiating to the outside of the atomic pool; (e) analyzing the signal light by using an optical polarizing method; (f) obtaining filtering signal. A semi-conductive laser is connected with a laser frequency locking circuit, the irradiated coupled laser is connected with a light barrier through a wave plate, a polarizing beam splitter and the atomic pool, the signal light passes through a variable optical attenuator, a polarized beam splitter, a reflector, a Glan prism and the atomic pool, is then subjected to quantum coherence induced optical rotation and is then transferred to be connected with an optical detector through the Glan prism; and a magnetic shielding room is arranged outside a heat preservation barrel, a heating wire and the atomic pool. The method is easy to be implemented and has the advantages of ultra-narrow bandwidth, high frequency tuning speed, simple structure and practicality.
Description
Technical field
The present invention relates to weak light detection or photon counting technique field, more specifically relate to a kind of method of inducing the atom filtering of rotation effect based on quantum coherent, also relate to a kind of device of inducing the atom filtering of rotation effect based on quantum coherent simultaneously, be applicable to free space quantum communications, (star-ground) laser communication, fluorescent type (thermometric, surveying wind) system such as laser radar extracts the low light level or photon signal in the bias light of wide spectrum, also be applicable to quantum devices such as making optical memory, high frequency photon counter and photon switch.
Background technology
The high-level efficiency quantum device that utilizes atom filtering method to make has been applied in long fields such as fluorescent type laser radar detection apart from atmospheric characteristics such as the demonstration of (machine-machine, star-star) laser communication, ocean temperature measurement, temperature and wind.Because in quantum communications, use the interference filter element of nm bandwidth magnitude, the ground unrest of airspace (daylight etc.) has the characteristic of higher light intensity and broad spectrum with respect to the photon signal of the information of carrying, and the photon signal that carries information can be submerged in the daylight ground unrest.How reducing the bit error rate that is caused by background noise in the free space quantum communications, survey and carry the faint light subsignal of information thereby be implemented under the daylight environment airspace background condition, is method or technical challenge.
Technical scheme at the existing related article of application background of the present invention and patent is as follows:
1) from " using the Space Quantum Communication device of atomic light filter " [Sun Xianping, Li Ruohong, Luo Jun, Zhan Mingsheng., Chinese invention patent number: ZL200310111370.4] and " Free-space quantum keydistribution with Rb vapor filters " [Xin Shan, Xianping Sun, Jun Luo, Zheng Tanand Mingsheng Zhan., Applied Physics Letter, 89,191121 (2006)] as can be known: A, technical scheme---because the color dispersion-type atomic light filter～the nm bandwidth of GHz bandwidth ratio interference filter element is narrow～more than 3 most magnitudes, for the free space quantum communications, select to use the chromatic dispersion atomic light filter to suppress background noise; B, its principle be utilize traditional faraday anomalous dispersion effect---strong magneto-optic effect makes the flashlight plane of polarization rotate; C, its structure are steam bubbles of the middle placement of Glan prism that a pair of plane of polarization quadrature is placed, and the outside of steam bubble is added with magnetic field; The problem of D, existence: although experimental demonstration shows that using the color dispersion-type atomic light filter to be one selects preferably in quantum communications, reduced the communication bit error rate, the quantum communication system performance obtains significantly to improve.But optics is relative with the sun and when not using micropore spatial filtering and time window filtering method when receiving, and still can increase the bit error rate, influences obtaining of safe key.
2) in order to address the above problem, at " atom filtering method and device that Raman light is amplified " [Dan Xin, Sun Xianping, Luo Jun, Zhan Mingsheng, Chinese invention patent number: 200810046862.2] and " Ultranarrow-bandwidth atomic filter with Raman light amplification " [Xin Shan, Xianping Sun, Jun Luo and Mingsheng Zhan., Optics Letters, 3316 (2008), 1842.] set up atom filtering method and device that a kind of Raman light is amplified, it has super narrow bandwidth (tens MHz) characteristic and can realize effective light amplification of tens of times of magnitude feeble signals, thereby more effectively suppresses background noise.A, technical scheme---utilize the Raman light amplification method, add the chromatic dispersion atom filtering method; B, its principle are signal to be carried out Raman light amplify, and re-use the chromatic dispersion atomic light filter and suppress bias light, gating signal light; C, its structure are: a branch of coupling light and a steam bubble combination are added a steam bubble as chromatic dispersion atom filtering device as the Raman light amplifier, and we are called two alveolitoids; The problem of D, existence: owing to used diatomic steam bubble array mode, complicated device.
3) problem in order to exist in the atom filtering method that overcomes above-mentioned pair of alveolitoid Raman light amplification, we are at application for a patent for invention " the aggregation type Raman strengthens atom vapor filtering signal method and apparatus " [Sun Xianping, Tan Zheng, Luo Jun, Zhan Mingsheng., Chinese invention patent application number: 200910273490.1] in realized a kind of new method, A, technical scheme---use single steam bubble, promptly amplify, also as atom filtering as Raman light; B, its principle be when coupling light and feeble signal light transmission by before the single steam bubble during part, its part is positioned in the magnetic field), can satisfy atom-exciting Raman gain condition, and by behind the steam bubble during part, because the outside is added with magnetic field, can satisfy the faraday anomalous dispersion condition of atom vapor again, reach Raman light amplification and chromatic dispersion atom filtering and realize by a steam bubble; C, its structure are: an atom steam bubble exterior portion be added with magnetic field, the two ends of the good outgoing steam bubble of flashlight incident are placed with the orthogonal Glan prism of plane of polarization; The problem of D, existence: although single alveolitoid method has been simplified the device of the atom filtering that two alveolitoid Raman light amplify, obtained gain factor greater than 10 times light amplification signal.Compare with chromatic dispersion atom filtering device, kept characteristics such as high rejection ratio, still, the live width of its filtering transmission peaks subtracts narrow undesirable, still needs to improve further.
In addition, for efficient raising, improvement in performance, use purpose widely, the always urgent demand of super narrow bandwidth atom filtering of development completely new approach.And, along with the development of quantum information technology, also need in fields such as light velocity regulation and control and quantum storages a kind of be different from the color dispersion-type wave filter, frequency of operation can be tuned to the super narrow bandwidth atom filtering method and the device of atomic resonance frequency.
Summary of the invention
The objective of the invention is to be to provide a kind of atom filtering method of inducing rotation effect based on quantum coherent.Easy to implement the method, have super narrow bandwidth, quick, the easy characteristics of frequency tuning.Compare with other laser light pump type atom filtering device,, greatly reduced the absorption of atomic medium, therefore, obtain higher filtering signal transmissivity flashlight because the present invention utilizes quantum coherent to induce rotation effect.
Another object of the present invention is to be to provide a kind of device of inducing the atom filtering of rotation effect based on quantum coherent.Simple in structure, structure-integrated, easy to operate, obtained～the super narrow bandwidth atom filtering of 10MHz transmission peaks, it approaches Rb atom nature bandwidth, only owing to the commercial lasers device live width of using limits; Also have characteristics such as the filtering operation wavelength can be regulated at a high speed, low-power coupled laser in several times of atom doppler linewidth scopes, have more practicality.
To achieve these goals, the present invention has adopted following technical measures:
The present invention proposes to utilize quantum coherent to induce the super narrow bandwidth atom filtering of rotation effect realization～10MHz in a former subpool.The flashlight of the use low light level or photon level is joined mutually with coupled laser and is restrainted the irradiated atoms pond, the quantum coherent that produces between the different transition of atom is interfered, be that electromagnetically induced is transparent, the absorption of flashlight (low light level or photon signal) in relevant atomic medium reduced, thereby significantly improve transmitance.Under the transparent situation of electromagnetically induced, flashlight (low light level or photon signal) transmission spectrum has characteristics such as super narrow bandwidth and high permeability.The present invention has placed a pair of Glan prism on flashlight (low light level or the photon signal) light path before and after the former subpool, be used to suppress that the atom filtering passband does not satisfy the transparent condition of electromagnetically induced outward and optical noise that rotation effect does not take place, the Glan prism before the former subpool is used for the polarization of control, conditioning signal light (low light level or photon signal); It is Left-hand circular polarization that polarization beam apparatus and λ/4 wave plates are used to regulate coupled laser.In atom degeneracy magneton level structure, when satisfying the condition of the transparent generation of electromagnetically induced, two kinds of circular polarization compositions of circular polarization coupling light and linear polarization flashlight (low light level or photon signal) constitute the asymmetry of the transparent subsystem of Λ configuration electromagnetically induced and the difference of different magneton energy level transition intensity respectively, cause the difference of two kinds of different circular polarization compositions refractive index in atomic medium of flashlight (low light level or photon signal), thereby cause the plane of polarization of linear polarization flashlight (low light level or photon signal) to rotate.Behind the former subpool of flashlight outgoing, carry out optics by the Glan prism that is positioned at the back and select polarization, obtain the atom filtering transmission spectrum by photodetection or photon counting in succession.Simultaneously, induce the optically-active condition because outer discontented capacity of wide spectrum bias light of the scattered light of coupled laser and passband is concerned with, its polarization direction does not change, and can not transmit the Glan prism of selecting polarization by optics, and be suppressed.
The invention provides a kind of atom filtering (method and apparatus) of inducing rotation effect based on quantum coherent, utilize the super narrow-band filtering characteristic of this invention, in the free space quantum communication system, can greatly reduce the bit error rate that causes by background noise in the communication process, to guarantee the formation efficiency of safe key.Than existing atom filtering method (for example, the faraday anomalous dispersion atom filtering device of～GHz bandwidth work), the present invention has more superior filtering characteristic: the super narrow bandwidth atom filtering of～10MHz magnitude and greater than 33% transmitance.The present invention also can be used for remote classical lasercom, in the systems such as fluorescent type laser radar, perhaps is applied to make quantum devices such as optical memory, high frequency photon counter and photon switch.
-induce the method for the atom filtering of rotation effect based on quantum coherent, the steps include:
(a) use a former subpool that is filled with alkali metal atom, it is equipped with heater coil, heat-preservation cylinder, magnetic shield room from inside to outside successively.A branch of circularly polarized coupled laser is radiated on the former subpool;
(b) flashlight of a branch of vertical curve polarization (low light level or photon signal) is transmitted in the former subpool and the coupled laser bundle of joining mutually;
(c) asymmetry of the transparent subsystem of Λ configuration electromagnetically induced of two kinds of circular polarization compositions formations of circular polarization coupling light and linear polarization flashlight (low light level or photon signal) and the difference of magneton energy level transition intensity, cause the difference of two kinds of different circular polarization compositions refractive index in atomic medium of flashlight (low light level or photon signal), thereby cause the plane of polarization of linear polarization flashlight (low light level or photon signal) to rotate, promptly quantum coherent is induced rotation effect;
(d) in succession, coupled laser and flashlight (low light level or photon signal) beam splitting and shining outside the former subpool;
(e) on flashlight (low light level or photon signal) light path, utilize optics to select polarizing method analytic signal light (low light level or photon signal), simultaneously, suppress the scattered light and the outer wide spectrum bias light of filter pass band of coupled laser;
(f) finally measure acquisition atom filtering signal by photodetection or photon counting mode.
In order to realize above-mentioned atom filtering method of inducing rotation effect based on quantum coherent, the present invention has adopted the atom filtering device of inducing rotation effect based on quantum coherent, and this device comprises magazine, laser frequency locking circuit unit, two λ/2 wave plates, two polarization beam apparatus, λ/4 wave plates, digital display temperature controller, magnetic shield room, two Glan prisms, photo-detector, semiconductor laser, catoptron, heater strip, former subpool, heat-preservation cylinder, variable optical attenuation sheet, aperture adjustable diaphragm, collimating mirror, light barrier.It is characterized in that: apparatus of the present invention all are integrated in the magazine, laser frequency locking circuit unit links to each other with semiconductor laser, the semiconductor laser of frequency stabilization is launched coupled laser and is linked to each other with a λ/2 wave plates, the coupled laser transmission is by a λ/2 wave plates, first polarization beam apparatus, λ/4 wave plates, former subpool, link to each other with light barrier, flashlight (low light level or photon signal) incident transmission is by being installed in the collimating mirror on the magazine, the aperture of aperture adjustable diaphragm, link to each other with the variable optical attenuation sheet, flashlight (low light level or photon signal) transmission is by the variable optical attenuation sheet, the 2nd λ/2 wave plates, second polarization beam apparatus, catoptron, second Glan prism, behind the former subpool, because quantum coherent induces rotation effect to make flashlight (low light level or photon signal) plane of polarization rotate, in succession, flashlight after the polarization direction changes (low light level or photon signal) transmission is by first Glan prism, be connected with photo-detector, digital display temperature controller links to each other with heater strip, the Kai Heguan of electric current in the control heater strip, magnetic shield room is positioned at heat-preservation cylinder, heater strip, the outside of former subpool, guarantee that the son work of former subpool Central Plains is not subjected to earth magnetic effect, heat-preservation cylinder is positioned at heater strip, outside the former subpool, be used to guarantee the working temperature in the former subpool, light barrier blocks the coupled laser of the former subpool of outgoing, reduces the influence of coupled laser scattered light to system.
Described coupled laser carries out frequency lock in the hyperfine transition of atom by laser frequency locking circuit unit, and its polarization direction is adjusted to Left-hand circular polarization.Coupled laser transmits along former subpool optical axis, at former subpool center with flashlight (low light level or photon signal) join mutually bundle and co-propagate, and beam splitting outside former subpool.
Described flashlight (low light level or photon signal) is adjusted to perpendicular linear polarization, passes through former subpool, first Glan prism with coupled laser with 0.1 °-1 ° low-angle transmission, arrives photo-detector.
Described first Glan prism is placed with the optical axis of second Glan prism is concentric, and the first Glan prism setting is consistent with the polarization angle of the flashlight of the former subpool of outgoing.
Atom is an alkali atom in the described former subpool, and its outside is equipped with heater strip, heat-preservation cylinder, magnetic shield room from inside to outside successively.
The concrete technical scheme of the atom filtering of the present invention-induce based on quantum coherent rotation effect is as follows:
(A) apparatus of the present invention mainly are made up of magazine, laser frequency locking circuit unit, two λ/2 wave plates, two polarization beam apparatus, λ/4 wave plates, digital display temperature controller, magnetic shield room, two Glan prisms, photo-detector, semiconductor laser, catoptron, heater strip, former subpool, heat-preservation cylinder, variable optical attenuation sheet, aperture adjustable diaphragm, collimating mirror, light barriers.
(B) coupled laser of frequency stabilization incides in the former subpool bundle of joining mutually by behind a λ/2 wave plates, first polarization beam apparatus and λ/4 wave plates jointly with flashlight (low light level or photon signal) in former subpool with a little angle.After the former subpool of coupled laser outgoing, blocked by the light barrier of surface blackening.
(C) aperture, variable optical attenuation sheet, the 2nd λ/2 wave plates and second polarization beam apparatus of collimating mirror, aperture adjustable diaphragm passed through in flashlight (low light level or photon signal) incident successively, change the direction transmission by second Glan prism via catoptron, measure by photodetector behind the former subpool and first Glan prism.
(D) the former subpool of apparatus of the present invention is wound with heater strip, is placed in the heat-preservation cylinder, and outermost is a magnetic shield room.The working temperature of the interior atomic medium of former subpool is controlled by digital display temperature controller and is shown.
(E) incide flashlight (low light level or photon signal) power bracket in apparatus of the present invention from the photon counting level to the mW magnitude, enter former subpool before, be chosen as the vertical curve polarization by second Glan prism.
(F) power bracket of coupled laser is a μ W magnitude to 100mW, and coupled laser and flashlight (low light level or photon signal) are with the low-angle bundle of joining mutually in former subpool.
(G) atomic medium polarizes under the coupled laser irradiation of Left-hand circular polarization, two kinds of circular polarization compositions that feasible and coupled laser satisfies the linear polarization flashlight (low light level or photon signal) of two-photon resonance condition jointly produce different refractivities, flashlight transmits a segment distance in atomic medium after, the rotation of certain angle can take place in its plane of polarization.Therefore, can transmit first Glan prism of selecting polarization by optics behind the former subpool of outgoing, and frequency is positioned at the scattered light of outer bias light of filter pass band and coupling light because the polarization direction does not change, and is then suppressed by first Glan prism.Use the present invention-induce the atom filtering method of rotation effect and the experiment that device obtains to see through spectrum as shown in Figure 3 based on quantum coherent, maximum transmission rate is greater than 33%, bandwidth～10MHz.
The present invention-induce the atom filtering device of optically-active to have the following advantages based on relevant:
(1) utilized the transparent effect of electromagnetically induced, reduced of the absorption of the sub-medium in former subpool Central Plains, reached filtering transmissivity greater than 33% to flashlight (low light level or photon signal).The number density of transmitance and atomic medium, the relating to parameters such as luminous power of coupled laser.
(2) experimental demonstration shows in whole frequency filtering adjustment process, obtains the super narrow atom filtering bandwidth less than 20MHz, and the narrowest is～10MHz to approach the natural width of atom.
(3) the present invention-induce the atom filtering transmission peaks of rotation effect to be tuned in the atom Doppler absorption peak scope based on quantum coherent is different from that therefore transmission peaks, has application fields more away from atomic resonance frequency in traditional color dispersion-type filtering method.
(4) use smaller power coupling light (＜20mW) realize the present invention-induce atom filtering of rotation effect easily based on quantum coherent; The power bracket of flashlight arrives the mW magnitude for the single photon level.
(5) can be in times over atom doppler bandwidth scope (～2GHz) can to realize that atom filtering sees through the fast frequency at peak tuning by regulating the coupling light frequency;
Compare with existing color dispersion-type atom filtering, the present invention has super narrow bandwidth, and frequency tuning is simple and easy, characteristics fast.Compare with other laser light pump type atom filtering device,, greatly reduced the absorption of atomic medium, therefore, obtain higher filtering signal transmissivity flashlight because the present invention utilizes quantum coherent to induce rotation effect.
Provided by the inventionly induce the atom filtering (method and apparatus) of rotation effect to can be effectively used under strong, wide spectrum bias light (for example daylight) condition, receive the low light level or photon signal based on quantum coherent, signal to noise ratio (S/N ratio) and acquisition of signal sensitivity have further been improved, all be with a wide range of applications in free space quantum communications, remote lasercom, fluorescent type laser radar field, also can be applicable to set up quantum devices such as optical memory, fast optical switch based or photon counter.
Description of drawings
Fig. 1 is a kind of based on the Rb atomic energy level synoptic diagram in the atom filtering experimental demonstration of quantum coherent rotation effect.
Rb atom 5S in the coupled laser excimer subpool among the figure
1/2(F=2) → 5P
1/2(F '=2) transition, two kinds of circular polarization composition σ of flashlight
+And σ
-Act on Rb atom 5S
1/2(F=1) → 5P
1/2(F '=2) transition.Utilization circular polarization coupling light and linear polarization in degeneracy magneton level structure are surveyed the different of the asymmetry of the transparent subsystem of Λ configuration electromagnetically induced that light constitutes and different magneton energy level transition intensity, cause the difference of two kinds of different circular polarization compositions refractive index in medium of surveying light, rotate thereby cause linear polarization to survey polarization surface.Induce rotation effect according to this quantum coherent, realized the tunable atom filtering of the super narrow bandwidth of the present invention.
Fig. 2 is a spectrogram that the transparent measurement of experimental demonstration atomic medium electromagnetically induced obtains.
The light/dark balance spectral line is an atom Doppler absorption peak, as the demarcation and the reference of wavelength.The aterrimus spectral line is based under the atomic energy level structural condition that Fig. 1 provides, when coupling light and flashlight are all the linearly polarized light of quadrature, and the transparent spectral line of atomic medium electromagnetically induced that obtains as the research checking measurements.At this moment, because the effect of the hyperfine energy level optical pumping of coupled laser, flashlight is corresponding to Rb atom 5S
1/2(F=1) → 5P
1/2The intensity of (F '=2) transition can increase.
Fig. 3 is the measurement spectrogram that an experimental demonstration acquisition the present invention is based on the atom filtering of quantum coherent rotation effect
Spectral line above the figure is a Rb atom D1 line Doppler absorption peak, is used for demarcation signal light frequency sweep limit.The atom filtering transmission spectrum that spectral line below the figure is to use apparatus of the present invention to obtain, the minimum bandwidth that sees through the peak is～10MHz that transmitance is 33%.When changing the coupling light frequency, it is tuning in several times of doppler linewidth scopes to realize that signal sees through the peak.
Fig. 4 is a kind of atom filtering schematic representation of apparatus based on the quantum coherent rotation effect.
Wherein magazine 1, laser frequency locking circuit unit 2, the one λ/2 wave plates 3, first polarization beam apparatus 4, λ/4 wave plates 5, digital display temperature controller 6, magnetic shield room 7, first Glan prism 8, photo-detector 9, semiconductor laser 10, second Glan prism 11, catoptron 12, second polarization beam apparatus 13, the 2nd λ/2 wave plates 14, heater strip 15, former subpool 16, heat-preservation cylinder 17, coupled laser 18, variable optical attenuation sheet 19, aperture adjustable diaphragm 20, collimating mirror 21, flashlight 22, light barrier 23.
Embodiment
Be described in further detail below in conjunction with accompanying drawing.
Material, shape and the structure of each parts of the present invention are at first described:
A) magazine 1 is by the rectangle box of aluminium sheet material, interior it all is blind hole that parts install and fix screw hole by the chemically blackening processing, during apparatus of the present invention work, except that the scattered light that 21 li accompaniment signal light 22 of collimating mirror of installing from magazine 1 enter, other direction ambient light can not enter;
B) laser frequency locking circuit unit 2, company and model are Toptica-LIR-110, are used for the frequency of the semiconductor laser 10 (company and model are Toptica-DL-100) that produces coupled laser 18 is locked;
C) λ/2 wave plates 3 are the Coherent-45-7184 half-wave plate, are used to change the polarization direction of coupled laser.
D) first polarization beam apparatus 4, company and model are Coheren-44-4505, are used to select see through the laser of a certain polarization, and with the power of a λ/2 wave plate fit adjustment coupled lasers 18.
E) λ/4 wave plates 5 are Coherent 45-7002 quarter-wave plate, are used for the coupled laser 18 of vertical curve polarization is become Left-hand circular polarization.
F) digital display temperature controller 6, and company and model are OMRON-E5CN, are used for former subpool 16 is carried out temperature survey, control and demonstration, to guarantee the atomicity density of atomic medium work;
G) magnetic shield room 7 is made by one deck or multilayer film alloy material, and cylinder design, size are according to the size of heat-preservation cylinder 17 and definite; Guarantee that 16 li atomic mediums of former subpool are operated in one and are not subjected in the environment that external magnetic field influences.
H) first Glan prism 8, company and model are Coherent-43-6782, the polarization that is used for flashlight (low light level or photon signal) 22 is selected.
I) photo-detector 9 is selected for the difference of photodetection mode, when the photodetection mode, use optical diode (company and model: Hamamatsu-S5821), photomultiplier (company and model: Chinese light-PMTH-S1 R5108 stands upright) etc., when the photon counting mode, use single photon counting module (company and model: EG﹠amp; G-SPCM-AQ-14Y) add NI-PCI-6602 counting/timer integrated circuit board etc.;
J) semiconductor laser 10 is commercial device or self-control devices of a purchase, has used the Toptica-DL-100 laser instrument in applicant's experimental demonstration, 795nm operation wavelength, the laser linewidth of～MHz magnitude;
K) second Glan prism 11, company and model are Coherent-43-6782, are used to select the flashlight 22 of polarization.
L) catoptron 12, and in the customization of Hefei goods and materials research institute of the Chinese Academy of Sciences, plating 795nm wavelength dielectric reflection film is used to change the transmission direction of flashlight (low light level or photon signal) 22.
M) second polarization beam apparatus 13, company and model are Coherent-44-4505, be used to select to transmit the laser of a certain polarization, and with the 2nd λ/2 wave plates 14 (company and the model: the Coherent-45-7184) power of fit adjustment flashlight (low light level or photon signal) 22 that place before it.
N) the 2nd λ/2 wave plates 14 are the Coherent-45-7184 half-wave plate, are used to change the polarization direction of flashlight (low light level or photon signal) 22.
O) heater strip 15 is looped around former subpool 16 outsides for using constantan wire from making armouring double wrap type, is used for former subpool 16 is carried out temperature control to change atomicity density; By digital display temperature controller 6 it is carried out switch, control.
P) former subpool 16 is determined according to the atomic medium type of selecting, and is made by Pyrex, 95 glass, quartz glass or stainless steel, is shaped as cylinder, square or rectangle; Incident and exit end window are the sheet glass that is parallel to each other; According to the needs of filter wavelength, be filled with the corresponding alkaline metal of wavelength in the former subpool.
Q) heat-preservation cylinder 17 is determined its structure according to former subpool 16, uses polytetrafluoroethylplastic plastic or epoxide resin material to make.
R) coupled laser 18, and what use in experimental demonstration is that Toptica-DL-100 semiconductor laser 10 produces, and operation wavelength is 795nm, and live width is the MHz magnitude.
S) the variable optical attenuation sheet 19, the adjustable neutral density attenuator that uses Coherent company to produce in experimental demonstration.
T) aperture adjustable diaphragm 20 is used for spatial filtering, signal beams size adjustment.
U) collimating mirror 21, use a plurality of optical mirror slips combination self-control, are used for received signal light, and adjusting, focus signal light (low light level or photon signal) 22 that can be in a big way.
V) flashlight (low light level or photon signal) 22 uses Toptica-DL-100 semiconductor laser 10 to produce the operation wavelength of 795nm, the live width of MHz magnitude, the sweep limit of～tens GHz in experimental demonstration.
W) light barrier 23, use the aluminium sheet of chemically blackening to make, and are used to stop the coupled laser 18 of transmission by former subpool 22, prevent the influence of its scattered light for system.
More than each parts all can purchase by those of ordinary skill in the art preparation or market.
A kind ofly induce the atom filtering device of rotation effect based on quantum coherent, it comprises magazine 1, laser frequency locking circuit unit 2, first, second λ/2 wave plates 3,14, first, second polarization beam apparatus 4,13, λ/4 wave plates 5, digital display temperature controller 6, magnetic shield room 7, first, second Glan prism 8,11, photo-detector 9, semiconductor laser 10, catoptron 12, heater strip 15, former subpool 16, heat-preservation cylinder 17, variable optical attenuation sheet 19, aperture adjustable diaphragm 20, collimating mirror 21, light barrier 23.Its annexation is: all parts of apparatus of the present invention all are placed on 1 li of a magazine, laser frequency locking circuit unit 2 links to each other with semiconductor laser 10, the coupled laser that the semiconductor laser 10 of frequency stabilization produces links to each other with a λ/2 wave plates 3, the coupled laser transmission is by a λ/2 wave plates 3, first polarization beam apparatus 4, λ/4 wave plates 5, former subpool 16, link to each other with light barrier 23, flashlight (low light level or photon signal) is from being installed in the collimating mirror incident on the magazine 1, transmission is by collimating mirror 21, the aperture of aperture adjustable diaphragm, link to each other with variable optical attenuation sheet 19, flashlight 22 (low light level or photon signal) transmission is by variable optical attenuation sheet 19, the 2nd λ/2 wave plates 14, second polarization beam apparatus 13, catoptron 12, second Glan prism 11, behind the former subpool 16, because quantum coherent induces rotation effect to make the plane of polarization of flashlight 22 (low light level or photon signal) rotate, in succession, first Glan prism 8 is passed in the postrotational flashlight 22 of polarization (low light level or photon signal) transmission, be connected with photo-detector 9, digital display temperature controller 6 links to each other with heater strip 15, the Kai Heguan of electric current in the control heater strip 15, magnetic shield room 7 is positioned at heat-preservation cylinder 17, heater strip 15, the outside of former subpool 16, guarantee that former subpool atom is in the utmost point low-intensity magnetic field, heat-preservation cylinder 17 is positioned at heater strip 15, outside the former subpool 16, guarantee the atom work intensity of former subpool 16, light barrier 23 blocks coupled laser, reduces the influence of coupled laser scattering to system.
Described coupled laser 18 by laser frequency locking circuit unit 2 with frequency lock in the hyperfine transition of atom, its polarization direction is adjusted to Left-hand circular polarization.Coupled laser 18 is along the 16 concentric optical axises transmission of former subpool, and with the flashlight 22 also co-propagate of bundle of joining mutually, beam splitting shines outside the former subpool 16 then at former subpool 16 centers.
Described incoming signal light 22 is adjusted to perpendicular linear polarization, to pass through former subpool 16, first Glan prism 8 with coupled laser 18 with 0.1 °-1 ° low-angle transmission, arrives photo-detector 9.
Described first Glan prism 8 is placed with the optical axis of second Glan prism 11 is concentric, and 8 settings of first Glan prism are consistent with the polarization angle of the flashlight 22 of the former subpool 16 of outgoing.
Atoms range is an alkali atom in the described former subpool 16, and its outside is equipped with heater strip 15, heat-preservation cylinder 17, magnetic shield room 7 from inside to outside successively.
The present invention is based on the relevant workflow of the atom filtering device of optically-active of inducing is:
Flashlight (low light level or photon signal) 22 and coupled laser 18 transmit incident atoms pond 16 in the same way.It is Left-hand circular polarization that first polarization beam apparatus 4 and λ/4 wave plates 5 are selected the polarization of coupled laser 18; Second polarization beam apparatus 13 and second Glan prism 11 guarantee that the polarization of flashlight (low light level or photon signal) 22 is the vertical curve polarization.Make flashlight (low light level or photon signal) 22 and coupled laser 18 with a little angle incident atoms pond 16 by accommodation reflex mirror 12, the heart bundle of joining mutually therein, the length that accommodation reflex mirror 12 is tried one's best flashlight (low light level or photon signal) 22 and the crossover range of coupled laser 18 in former subpool 16.The optical axis that first Glan prism 8 and second Glan prism 11 are set forms certain angle, thereby suppresses the scattered light that the outer ground unrest of filter pass band, coupled laser produce at atom pool wall and atomic medium.Apparatus of the present invention have realized super narrow bandwidth filtering, extract actual signal light (low light level or photon signal) from ground unrest, the squelch ratio outside the filter pass band reaches～and 10
5
Below in conjunction with accompanying drawing the atom filtering method that the present invention is based on relevant optically-active is elaborated, the steps include:
(a) carry out frequency stabilization by laser frequency locking circuit unit 2 noise spectra of semiconductor lasers 10, semiconductor laser 10 emission coupled lasers 18, it is through a λ/2 wave plates 3 and polarization beam apparatus 4, and is adjusted to Left-hand circular polarization behind λ/4 wave plates 5, irradiated atoms pond 16.
(b) the former subpool that uses 16 is outer to be added with magnetic shield room 7, be positioned at atomic medium in the constant Weak magentic-field of shielding earth magnetism by coupled laser 18 irradiations of Left-hand circular polarization after, atomic medium is polarized.
(c) after flashlight (low light level or photon signal) 22 goes into to inject apparatus of the present invention through the collimating mirror 21 on the magazine 1, transmission is successively by aperture adjustable diaphragm 20, variable optical attenuation sheet 19, the 2nd λ/2 wave plates 14 and second polarization beam apparatus 13, change the beam Propagation direction by catoptron 12, again through becoming the vertical curve polarized light behind second Glan prism 11, in succession, incide 16 li of former subpools.
(d) vertically flashlight (low light level or the photon signal) 22 of polarization transmits by former subpool 16 in the same way with 0.1 ° of-1 ° of angle with circularly polarized coupled laser 18, and the bundle of joining mutually in atomic medium.
(e) when the frequency of flashlight (low light level or photon signal) 22 and coupled laser 18 satisfies the two-photon resonance condition in atomic medium, because quantum coherent is induced rotation effect, the plane of polarization of flashlight (low light level or photon signal) 22 rotates.
(f) last, flashlight (low light level or photon signal) 22 transmission are carried out photodetection or photon counting by behind first Glan prism 8 by photo-detector 9.Do not select polarization conditions because the optics of first Glan prism 8 is not satisfied in the scattered light of coupled laser 18 and bias light polarization direction, in its process, suppressed by first Glan prism 8.And between the flashlight (low light level or photon signal) 22 of coupled laser 18 and vertical polarization an angle is arranged, and beam splitting after 16 li of former subpools are joined bundle mutually, the outgoing transmission is stopped by the light barrier 23 of blacking.
According to the invention described above method, and, the atom filtering based on the quantum coherent rotation effect provided by the present invention (method and apparatus) is described in further detail to use alkaline metal rubidium (Rb) atom vapor to be example.
In experimental demonstration, the present invention-induce all component of the atom filtering of rotation effect to be installed in 1 li of magazine together based on quantum coherent.Laser frequency locking circuit unit 2 is locked in the coupled laser 18 of semiconductor laser 10 emissions on the Rb atomic spectral line of selection, the bandwidth of coupled laser 18 is the MHz magnitude, power is scalable in the 0-100mW scope, and wavelength tuning is near the D1 resonance line 795nm of alkaline metal rubidium (Rb) atom.
The operation wavelength of the one λ/2 wave plates 3 and the 2nd λ/2 wave plates 14 is 795nm.Be respectively applied for the polarization direction that changes coupled laser 18 and flashlight (low light level or photon signal) 22.λ/4 wave plates 5 make coupled laser 18 be adjusted to Left-hand circular polarization.
The transparent surface of first polarization beam apparatus 4 and second polarization beam apparatus 13 is coated with the 795nm anti-reflection film, and extinction ratio is 1000: 1, is respectively applied for coupled laser 18 and flashlight (low light level or photon signal) 22 transmission of selecting polarization.
The extinction ratio of first Glan prism 8 and second Glan prism 11 is 10
5, transparent surface plating 795nm anti-reflection film, the flashlight of a branch of 795nm of being operated in wavelength (low light level or photon signal) 22 transmission are passed through from the axle center of second Glan prism 11 and first Glan prism 8.
In the experimental demonstration, the Rb atom vapor that former subpool is 16 li is as the optically-active medium, and the structure of the density of Rb atom, magnetic field environment, former subpool etc. all can influence optically-active efficient.The Rb atom vapor density of digital display temperature controller 6 by working in the former subpool 16 of heater strip 15 controls, heat-preservation cylinder 17 reduces the thermal loss of former subpool 16, magnetic shield room 7 has guaranteed that the Rb atom vapor is operated in the Weak magentic-field environment of a requirement, makes it not to be subjected to the influence of terrestrial magnetic field.The end face of former subpool 16 is sheet glass hot melt veneer and keeps completely parallel cylindrical Simon Rex (Pyrex) glass envelope of sending, and the long scope of bubble is 20mm-200mm, and diameter range is 10mm-50mm, is filled with a few mg alkaline metal rubidiums (Rb) in the bubble.
The aperture size of adjustment aperture adjustable diaphragm 20 can be carried out shaping to the light beam of the flashlight (low light level or photon signal) 22 of incident.
Flashlight (low light level or photon signal) 22 and coupled laser 18 transmit in the same way and are radiated at former subpool 7, in the Rb atom vapor, intersect and close bundle, when their frequency satisfies the two-photon resonance condition, because quantum coherent is induced rotation effect, the plane of polarization of flashlight (low light level or photon signal) 22 rotates.Select first Glan prism 8 of polarization by optics in flashlight (low light level or photon signal) 22 transmission of former subpool outgoing, the photo-detector that is comprised 795nm by response wave length carries out opto-electronic conversion or photon counting, the atom filtering that obtains super narrow bandwidth sees through the peak, and the scattered light of coupled laser 18 and bias light do not satisfy the optics selection polarization conditions of first Glan prism 8, then are suppressed.With flashlight (low light level or photon signal) 22 beam splitting, reach light barrier 23 at last and be blocked behind the former subpool of coupled laser 18 outgoing.
Be example all in the foregoing description with alkaline metal rubidium (Rb) atom filtering, in specific implementation process, the present invention relates to other alkali metal atom-potassium (K), sodium (Na) and caesium (Cs), need select laser frequency locking circuit unit, the laser instrument corresponding to the alkali atom spectral line, the parameters such as optical device, magnetic shield room, atom pool structure device and atomicity density of operation wavelength plated film respectively.
Claims (6)
1. the method for an atom filtering of inducing rotation effect based on being concerned with the steps include:
(a) use a former subpool that is filled with alkali metal atom, heater strip, heat-preservation cylinder, magnetic shield room are housed from inside to outside successively, a branch of circularly polarized coupled laser is radiated on the former subpool;
(b) the flashlight incident of a branch of vertical curve polarization is transmitted in the former subpool to intersect with coupled laser and closes bundle;
(c) asymmetry of the transparent subsystem of Λ configuration electromagnetically induced of two kinds of circular polarization compositions formations of the flashlight of circularly polarized coupling light and linear polarization and the difference of magneton energy level transition intensity, cause the difference of two kinds of different circular polarization compositions refractive index in atomic medium of flashlight, cause linear polarization signal polarization surface to rotate, promptly quantum coherent is induced rotation effect;
(d) in succession, coupled laser and flashlight beam splitting and shine outside the former subpool;
(e) on the flashlight light path, utilize optics to select polarizing method analytic signal light, simultaneously, suppress the scattered light and the outer wide spectrum bias light of atom filtering passband of coupled laser;
(f) finally measure acquisition atom filtering signal by photodetection or photon counting mode.
2. the described a kind of device of inducing the atom filtering of rotation effect based on quantum coherent of claim 1, it comprises magazine (1), laser frequency locking circuit unit (2), first wave plate (3), first polarization beam apparatus (4), digital display temperature controller (6), semiconductor laser (10), former subpool (16), light barrier (23), it is characterized in that: all other parts all are placed on magazine (1) lining, laser frequency locking circuit unit (2) links to each other with semiconductor laser (10), the semiconductor laser of frequency stabilization (10) is launched coupled laser (18) and is linked to each other with first wave plate (3), coupled laser (18) transmission is successively by first wave plate (3), first polarization beam apparatus (4), wave plate (5), former subpool (16), link to each other with light barrier (23), flashlight (22) is by collimating mirror (21) incident that is installed on the magazine (1), transmission is by collimating mirror (21), the aperture of aperture adjustable diaphragm (20), link to each other with variable optical attenuation sheet (19), flashlight (22) transmission is successively by variable optical attenuation sheet (19), second wave plate (14), second polarization beam apparatus (13), catoptron (12), behind second Glan prism (11), incide former subpool (16), flashlight after the polarization direction changes (22) transmission is by the atomic medium of former subpool (16) lining, first Glan prism (8), be connected with photo-detector (9), digital display temperature controller (6) links to each other with heater strip (15), magnetic shield room (7) is positioned at heat-preservation cylinder (17), heater strip (15), the outside of former subpool (16), heat-preservation cylinder (17) is positioned at heater strip (15), outside the former subpool (16).
3. a kind of device of inducing the atom filtering of rotation effect based on quantum coherent according to claim 2, it is characterized in that: described coupled laser (18) by laser frequency locking circuit unit (2) with frequency lock in the hyperfine transition of atom, its polarization direction is adjusted to Left-hand circular polarization.
4. according to claim 2ly a kind ofly induce the device of the atom filtering of rotation effect based on quantum coherent, it is characterized in that: described incoming signal light (22) is adjusted to perpendicular linear polarization, with coupled laser (18) with 0.1
0-1
0Angle.
5. a kind of device of inducing the atom filtering of rotation effect based on quantum coherent according to claim 2, it is characterized in that: the concentric placement of optical axis of described first Glan prism (8) and second Glan prism (11), first Glan prism (8) are provided with consistent with the polarization angle of the flashlight (22) of the former subpool of outgoing (16).
6. a kind of device of inducing the atom filtering of rotation effect based on quantum coherent according to claim 2, it is characterized in that: the interior atoms range of described former subpool (16) is an alkali atom, and its outside is equipped with heater strip (15), heat-preservation cylinder (17), magnetic shield room (7) from inside to outside successively.
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| CN110570890A (en) * | 2019-09-29 | 2019-12-13 | 中国科学技术大学 | Nonreciprocal single photon quantum memory |
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| CN108475353A (en) * | 2015-12-31 | 2018-08-31 | 国际商业机器公司 | Using the muliti-qubit adjustable coupling structure of fixed frequency superconductive quantum bit |
| CN108475353B (en) * | 2015-12-31 | 2022-04-26 | 国际商业机器公司 | Multi-qubit tunable coupling mechanism using fixed-frequency superconducting qubits |
| US10795171B2 (en) | 2016-07-27 | 2020-10-06 | Wuhan Institute Of Physics And Mathematics Chinese Academy Of Sciences | Optical-fiber atomic light-filtering apparatus |
| CN110133878A (en) * | 2019-04-30 | 2019-08-16 | 陕西师范大学 | A kind of ultra-narrow band faraday normal dispersion atomic light filter and the filtering method transparent based on chamber electromagnetically induced |
| CN110133878B (en) * | 2019-04-30 | 2022-06-10 | 陕西师范大学 | Ultra-narrow-band Faraday normal dispersion atomic filter based on cavity electromagnetic induction transparency and filtering method |
| CN110570890A (en) * | 2019-09-29 | 2019-12-13 | 中国科学技术大学 | Nonreciprocal single photon quantum memory |
| EP4012943A1 (en) * | 2020-12-14 | 2022-06-15 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for spatial filtering of a quantum signal for free-space quantum communication |
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