CN202218230U - Automatic basis vector adjusting device for quantum communication system - Google Patents

Abstract

The utility model discloses an automatic basis vector adjusting device for a quantum communication system, which comprises a rotating motor component, a half-wave plate, a motor controller, a real-time controller and a rotating transformer in the quantum communication system. The real-time controller reads the position of a telescope in real time through the rotating transformer, works out the deflection angle of signal light according to an algorithm and the angle required to rotate of the half-wave plate, and generates control signals to be transmitted to the motor controller; and after receiving the control signals, the motor controller controls a motor to rotate the half-wave plate to a proper position according to the position of the half-wave plate detected by a photoelectric encoder, and to rotate the signal light to a proper polarization state, so that the quantum communication system can correctly detect the polarization information of quantum light through a basis vector. The device solves the problem that the polarization direction of the signal light is changed during quantum communication due to the change of azimuth of the telescope during tracking, so that a receiving terminal can correctly detect the polarization state of the signal light under a specific basis vector standard.

Description

The basic vector automatic regulating equipment that is used for quantum communication system

Technical field

This patent relates to free space quantum communications technology, is specifically related to a kind of basic vector automatic regulating equipment that is used for quantum communication system, and it is used for quantum communications are automatically adjusted because of thick change of polarization of following the tracks of the flashlight that is caused.

Technical background

Mainly be by having the light quantum transmission information of special polarization state in the space scale quantum communications; The polarization state of judging light quantum needs unified standard; Introduce a kind of specific quadrature two-dimensional coordinate system in the native system as the standard of judging the photon polarization state; And be used in the whole communication system judge that the coordinate system of flashlight polarization state is consistent, this coordinate system is called basic vector.Transmitting terminal has the quantum light of polarization information with basic vector as standard emission, and receiving terminal is that standard is extracted quantum polarisation of light information with the basic vector equally after receiving quantum light.

In the space scale quantum communications, satellite rotates around the earth along track, the receiving station earthward that does not the stop light that transmits, and the grounded receiving station needs constantly adjustment telescope attitude so that catch the signal that satellite transmits is come, shown in I among Fig. 2.Telescope mainly contains two kinds of attitudes in the lock-on signal light time to be changed: pitch orientation rotation and horizontal direction rotation.Shown in II among Fig. 2, be as the criterion with earth axes, vertical ground upwards is the Z axle, horizontal direction is confirmed X axle and Y axle with the right-hand rule.The angle of regulation pitch orientation rotation is the angle of pitch, by-Z axially+Z-direction just rotates to be, scope is spent to 90 degree for-90; The angle of horizontal direction rotation is the azimuth, is axial dextrorotation for just with+Z axle, and scope is spent to 180 and spent (the actual angle of pitch of telescope and azimuthal scope are smaller) for-180.

For being transferred in the light path system of back, handles the flashlight that telescope is captured; Need in telescopical turning arm, reflected light path be installed; As shown in Figure 3; The left side is a telescope turning arm index path, and wherein 6 is that telescope lens barrel, 7 is that telescope turning arm, 8 is that incident ray, 9 is that horizontal reflection light, 10 is vertical reflection light.Can find out by Fig. 3, when telescope rotates, can influence the polarization direction of flashlight in the reflected light path.The direction that specified signal light is propagated is the Z axle, and the basic vector coordinate is perpendicular to the Z axle, and satisfies the right-hand rule, and the represented X-Y axle of A is the basic vector coordinate of incident light 8 among the figure.When the telescopical angle of pitch changes, then can cause the polarization rotation of telescope horizontal reflection light 9; If the telescope lens barrel angle of pitch is a; Regulation is along the direction of propagation of flashlight; The dextrorotation of flashlight polarization state is for just, and then the angle of the polarization direction of horizontal reflection light 9 rotation is a, shown in B among Fig. 3; Wherein dotted line is represented the basic vector of whole system, the plane rotation status at X-Y axle expression signal polarisation of light direction place.When turning arm drives the rotation of telescope horizontal direction, can cause that then turning arm reflexes to the flashlight generation rotation of back light path vertically upward, shown among Fig. 3 10; Establishing telescope lens barrel horizontal azimuth equally is b, defines dextrorotation equally for just, and then the angle of vertical reflection polarisation of light direction rotation is b, shown in C among Fig. 3.

Can draw according to above analysis: angle of pitch a can cause the 9 polarization dextrorotation of lens barrel horizontal reflection light, and azimuth b causes turning arm vertical reflection light 10 polarization right avertence.Because the lens barrel angle of pitch and azimuthal stack; The polarization direction of the vertical emergent ray of turning arm is a+b with respect to the basic vector direction deflection angle of incident ray; So when the angle of polarization is after the flashlight of α gets into telescope; Can converge on the middle speculum of lens barrel through the concave mirror of telescope lens barrel bottom; Through the lens barrel speculum light level is reflexed to the reflected light path in the turning arm, if the angle of pitch a of lens barrel is non-vanishing, horizontal reflection this moment light the angle of X axle of the angle of polarization and basic vector will be changed to α+a.When light gets into reflected light path, at first need light be become directional light, and then reflex to the back light path through three plane mirrors through a slice convex lens.When flashlight reflexed to the back light path vertically upward through last piece plane mirror, if this moment, telescopical azimuth b was non-vanishing, the X axle clamp angle of the polarization direction of flashlight and basic vector will become α+a+b so, shown in D among Fig. 3.

Quantum receiving terminal in Fig. 1 quantum communication system 5 is fixed in the light path of back, must its polarization state be rotated to the polarization state that receiving terminal can correctly detect with the basic vector standard before flashlight detects, and this just need increase the optically-active element in the light path of back.Adopt half-wave plate that the flashlight polarization is rotated in the native system, when half-wave plate quick shaft direction and basic vector X axle clamp angle were θ (counter clockwise direction for just), its Jones matrix was:

$\left[\begin{array}{c}\cos 2\mathrm{\θ},\sin 2\mathrm{\θ}\\ \sin 2\mathrm{\θ},-\cos 2\mathrm{\θ}\end{array}\right]$

When light vector became the α angle with the X axle, its Jones matrix was:

$E_{\mathrm{\α}}=\left[\begin{array}{c}\cos \mathrm{\α}\\ \sin \mathrm{\α}\end{array}\right]$

When this light vector transmission half-wave plate, the Jones matrix of emergent ray is:

$E_{\mathrm{out}}=\left[\begin{array}{c}\cos 2\mathrm{\θ},\sin 2\mathrm{\θ}\\ \sin 2\mathrm{\θ},-\cos 2\mathrm{\θ}\end{array}\right]\left[\begin{array}{c}\cos \mathrm{\α}\\ \sin \mathrm{\α}\end{array}\right]=\left[\begin{array}{c}\cos (2\mathrm{\θ}-\mathrm{\α})\\ \sin (2\mathrm{\θ}-\mathrm{\α})\end{array}\right]$

Be changed to 2 θ-α so see through the angle of polarization of the emergent ray of half-wave plate by α.

According to preceding surface analysis; If incoming signal light polarization direction and X-direction angle are α among Fig. 3; Then because the influence of telescope rotation; Reflect the angle that the polarization direction of the flashlight of light path backward has been rotated counterclockwise (a+b) through turning arm, promptly this moment, flashlight and horizontal direction angle were α+(a+b).If it is as shown in Figure 4 that the angle of the quick shaft direction of half-wave plate and basic vector X-direction is set to

; Wherein angle 12 is half-wave plate and basic vector X axle clamp angle, and angle 13 is a flashlight polarization deflection angle.According to half-wave plate revolve the ripple principle, the flashlight polarization angle that half-wave plate is crossed in transmission is:

$2\left(\frac{a+b}{2}\right)-[\mathrm{\α}+(a+b)]=-\mathrm{\α}$

The angle of polarization that is flashlight finally is changed to-α by α, only needs in the quantum test side like this negate of detected polarization angle just can correctly be obtained the signal polarized state of light.

The flashlight of tracking satellite emission because telescope needs real-time adjustment attitude in communication, so the basic vector regulating system also needs in real time adjustment automatically to reflex to the flashlight polarization state of back light path, this just needs to introduce automatic control system.As shown in Figure 1: electric rotating machine assembly 1 can record the position of rotation of half-wave plate 2 through photoelectric encoder; Resolver 5-1 can record telescopical position of rotation; So can utilize real-time controller to read telescopical position in real time through resolver; Go out the angle of flashlight deflection and the angle of half-wave plate needs rotation according to algorithm computation noted earlier again; Generate control signal then and send to electric machine controller; Electric machine controller 3 is received the half-wave plate position that records according to photoelectric encoder after the control signal, and the control motor rotates to the appropriate location with half-wave plate; Thereby flashlight is rotated to appropriate polarization state, so that the quantum receiving terminal can correctly detect quantum polarisation of light information through basic vector.

Summary of the invention

The present invention is directed between star ground in the quantum communication; The flashlight rotation that the transformation space angle that the telescope lens barrel does not stop owing to tracking satellite is caused; Thereby make signal receiving end can't correctly detect the problem of revolving the light vector information after the change, a kind of effective basic vector automatic regulating equipment is provided with fixing basic vector.This device rotates the light vector that changes the polarization direction according to the data of resolver in real time through controlled half-wave plate, through a series of conversion, and can be when making light vector arrive communication terminal by correct the detecting of quantum receiving terminal.Solved between star ground in the quantum communication and caused flashlight polarization direction rotation change in the reflex circuit, caused receiving terminal can't correctly detect the problem of quantum light polarization state because the telescope Space Angle changes.

This device is the wave property of revolving of utilizing half-wave plate, and the flashlight that changes polarization state is rotated to appropriate angle, and then through a series of conversion, thus make the quantum receiving terminal can through with the unified basic vector of quantum transmitting terminal with correct the detecting of flashlight.Wherein telescopical space angle can be through being installed in the telescope lens barrel feathering axis and the resolver on the pitching rotating shaft read, the anglec of rotation of half-wave plate then can be controlled through photoelectric encoder and electric machine controller.

Set a kind of specific quadrature two-dimensional coordinate system in the device as the standard of judging the photon polarization state, this coordinate system is called basic vector; Transmitting terminal is the quantum light that standard emission has certain polarization state with the basic vector, and receiving terminal is standard detection signal polarized state of light with the basic vector.Use this device, quantum light transmitting terminal and receiving terminal can use the criterion of unified basic vector as light vector.Flashlight gets into telescope turning arm reflected light path; Polarization state can change; Before arriving the quantum receiving terminal; Through half-wave plate quantum polarisation of light direction is rotated to the negative direction of initial polarization direction, just can utilize predetermined basic vector to detect the signal polarized state of light at receiving terminal like this, and the variation of the flashlight polarization direction of not worrying being caused by the telescope tracking satellite.

The structure of this patent quantum communications basic vector automatic regulating equipment is as shown in Figure 1, and its structure comprises: the resolver 5-1 in electric rotating machine assembly 1, half-wave plate 2, electric machine controller 3, real-time controller 4 and the quantum communication system 5.Wherein:

1. electric rotating machine assembly 1 is made up of electric rotating machine, photoelectric encoder and half-wave plate mounting base, and half-wave plate 2 is fixed on the half-wave plate pedestal, and the half-wave plate mounting base is connected with electric rotating machine through the endless screw-worm gear transmission; Photoelectric encoder is installed on the electric rotating machine, the main position of rotation of being responsible for measuring the electric rotating machine assembly, and its required precision reaches 0.1 degree; Electric rotating machine adopts controlled direct current machine or stepping motor, and reaction speed is in 0.3s, and electric rotating machine drives the rotation of half-wave plate mounting base through the endless screw-worm gear transmission, and the running accuracy of half-wave plate mounting base is 0.1 degree;

2. half-wave plate 2 is chosen quantum communication system 5 needs signal light wavelength to go into accordingly/2 half-wave plates;

3. electric machine controller 3 is used for reading photoelectric encoder data and control electric rotating machine, and has the function of control able to programme;

4. real-time controller 4 programming device that adopts computers or have the floating-point operation function is used for reading in real time the resolver data, and calculating half-wave plate needs the anglec of rotation, the control electric machine controller;

5. resolver 5-1 is two resolvers, is installed in respectively on telescopical pitch axis of optic terminal and the trunnion axis, is responsible for reading telescope horizontal azimuth and pitch angle data, and its certainty of measurement is 0.1 degree.

Electric rotating machine assembly 1 is installed in behind the telescope of quantum communication system 5 in the light path; Half-wave plate 2 is fixed in the half-wave plate mounting base on the electric rotating machine assembly 1, and flashlight needs could arrive the quantum signal receiving terminal through half-wave plate earlier; Electric machine controller 3 is connected on the electric rotating machine assembly so that read photoelectric encoder data and control electric rotating machine through data wire; Real-time controller 4 connects resolver 5-1 through a data lines and reads telescope Space Angle data, connects electric machine controller 3 through an other data lines and comes to transmit control signal to electric machine controller; Resolver 5-1 be installed in respectively on the telescope feathering axis with the pitching rotating shaft on, measuring telescope horizontal azimuth and pitch angle data respectively, and send data to real-time controller 4 through data wire.

Electric rotating machine assembly 1 records the position of rotation of half-wave plate 2 through photoelectric encoder, and resolver 5-1 records telescopical position of rotation, utilizes real-time controller 4 to read telescopical position in real time through resolver; Go out the angle of flashlight deflection and the angle of half-wave plate needs rotation according to algorithm computation again; Generate control signal and send to electric machine controller 3; Electric machine controller 3 is received the half-wave plate position that records according to photoelectric encoder after the control signal; The control motor rotates to the appropriate location with half-wave plate 2, flashlight is rotated to appropriate polarization state, so that quantum communication system 5 can correctly detect quantum polarisation of light information through basic vector.

It is following that basic vector is regulated concrete steps automatically:

1. set the control time interval t of real-time controller 4 according to the variation maximal rate that detects quantum polarization state and telescope lens barrel Space Angle; Per interval t real-time controller will send an instruction to resolver 5-1, reads the data of resolver 5-1;

2. the turning arm motor is through the real-time signal acquisition light of adjustment telescope; When the angle of polarization is after the angle is the flashlight entering telescope of α; If telescopical angle of pitch a and feathering angle b are non-vanishing; Reflex to the flashlight polarization direction of back light path and the X axle clamp angle of basic vector and will become α+a+b, telescopical angle of pitch a and feathering angle b can feed back to real-time controller 4 through resolver 5-1;

3. real-time controller 4 reads telescopical angle of pitch a and telescopical horizontal azimuth b respectively through resolver 5-1; Calculating the flashlight angle of polarization through flashlight angle of polarization rotation principle of stacking is α+a+b; And go out the angle

of half-wave plate needs rotations according to half-wave plate optically-active property calculation thus generate control signal, and send to electric machine controller 3 to control signal;

4. electric machine controller 3 receives control signal; Start the electric rotating machine rotation half-wave plate 2 in the electric rotating machine assembly 1; And constantly measure the angle of half-wave plate through photoelectric encoder; When half-wave plate rotates to quick shaft direction and just stopped the rotation for

time in basic vector X axle clamp angle, wait for next bar instruction of real-time controller 4;

5. the flashlight angle of polarization that reflexes to the back light path is α+a+b, and flashlight can first transmission be crossed half-wave plate 2 before arriving the quantum receiver, because the optically-active characteristic of half-wave plate, the angle of polarization of flashlight can become-α;

6. the quantum receiver receives flashlight; With preset basic vector is that standard detection goes out quantum polarisation of light angle and is-α; And this angle negate just obtained the polarization of incident light angle [alpha]; Automatically regulate with this basic vector of just having accomplished quantum communication system, make the altered flashlight of polarization state can be finally by correct detecting.

The beneficial effect of this patent is: adopt the basic vector controlled system with self-regulation can effectively solve the polarization variations that the telescope dimensional orientation changes the flashlight in the light path that causes in the quantum communication system; Can real-time and effective the polarization direction of flashlight be rotated to appropriate angle; Thereby what make that the quantum receiving terminal can be correct detects the flashlight polarization state, has guaranteed that quantum communications carry out smoothly.

Description of drawings

Fig. 1 is a basic vector automatic regulating equipment structure chart, among the figure:

1. electric rotating machine assembly 2. half-wave plates 3. electric machine controllers

4. real-time controller 5. quantum communication system 5-1. resolvers.

Fig. 2 is telescope space angle explanation diagram: among the figure:

I representes the space sketch map of telescope tracking satellite;

II representes telescope space angle coordinate diagram.

The diagram of the reflected light path flashlight rotation change that Fig. 3 is caused for telescope rotation, among the figure:

6. telescope 7. turning arms 8. incident raies

9. horizontal reflection light 10. vertical reflection light

A. the incident ray basic vector coordinate B. horizontal reflection light polarization anglec of rotation

C. the total anglec of rotation of vertical reflection light polarization anglec of rotation D. reflected light path polarization.

Fig. 4 is a half-wave plate placement location sketch map.

Fig. 5 is a basic vector Automatic adjustment method program flow diagram.

Embodiment

The whole instance system that can be used for quantum communications basic vector automatic regulating system is as shown in Figure 1: the electric rotating machine assembly PRM1-Z7 that electric rotating machine assembly 1 adopts THORLABS company to produce, and its apparent size 68mm, its half-wave plate pedestal internal diameter is 27mm; It is the direct current machine that photoelectric encoder and the reaction speed of 0.1 degree is 0.2 second that this electric rotating machine assembly comprises precision; Direct current machine adopts threaded rod to be connected on the half-wave plate pedestal of rotary components; Half-wave plate is fixed on the half-wave plate pedestal of electric rotating machine assembly, through the direct current machine driven rotary; Electric machine controller 3 adopts the APT direct current machine servo controller TDC001 that produces with the supporting THORLABS company of electric rotating machine assembly, and this electric machine controller can carry out programming Control through the APT series control program that THORLABS company provides; The laser that adopts 850nm in this instance system is as flashlight; So half-wave plate adopts the half-wave plate of 800 to 900nm wave bands; It is polished into the circle that diameter is 26mm, is fixed on the electric rotating machine assembly PRM1-Z7, and be installed in the back light path of quantum communication system 5; Resolver 5-1 adopts the resolver of customization, and certainty of measurement can reach 0.01 degree, can reach 0.1 degree so the basic vector of this instance system is regulated static precision; Real-time controller 4 adopts computer to realize, logical middle control circuit obtains the resolver data, connects electric machine controller through serial port, writes the control desk program on computers and comes to carry out in real time Data Acquisition, calculate, and the transmission of motor instruction.Electric machine controller TDC001 in this instance system can carry out programming Control through the APT series control program that THORLABS company provides.Mainly use the ActiveX control of two APT softwares: MG17Motor and MG17Logger, wherein the MG17Motor control is the Electric Machine Control control, and MG17Logger is a motor instruction daily record control.Function through calling in the MG17Motor control can be realized the control of motor operation and the position of reading the rotary components rotation, and the MG17Logger major function is to show the instruction that APT direct current machine servo controller is sent.

Electric rotating machine assembly PRM1-Z7 carries vernier dial, and the vernier dial precision is 0.1 degree.The method that its photoelectric encoder adopts the contact to make zero, dump and restart photoelectric encoder reading are zero.So making the photoelectric encoder reading is the absolute position, in the time of must starting motor is definitely made zero at every turn.This basic vector automatic regulating system instance The software adopted C++ programming; Need add the MG17Motor control during programming; At first to the hardware sequence number in the control property be changed into the hardware sequence number of DC motor controller TDC001, come the starter motor controller through control instruction startctrl () during start-up routine.Adopt the programming mode of two-wire journey in the instance, main thread mainly is responsible for reading the resolver data in real time, and carries out the data computation conversion, sends instruction to DC motor controller then.Can trigger a sub-thread after starting TDC, this sub-thread mainly is responsible for constantly reading the absolute position of half-wave plate and showing to the electric rotating machine assembly.Program flow diagram is as shown in Figure 5.

Coming further below in conjunction with Fig. 1, elaboration the present invention can carry out the self-regulating practical implementation step of basic vector:

1. the required precision that detects the quantum polarization state is ± 0.5 degree; And the pace of change of telescope lens barrel Space Angle was for 0.2 degree/second to the maximum in this example approach; So can be on computers control time of control desk be set to 1s; Because can ignore time-delay in 0.2 second of rotary components during control in real time, basic vector regulating system precision of real time control can reach 0.3 degree.The control desk program is every can send an instruction to resolver 5-1 at a distance from 1s, reads the data of resolver 5-1;

In this experiment we adopt wavelength be the 45 degree polarised lights of 850nm as flashlight, during experiment constantly the pitch axis resolver to record the telescopical angle of pitch be 8.93 degree, it is 12.46 degree that the horizontal rotational shaft transformer records telescopical azimuth.When flashlight passed through the turning arm reflected light path, light path did not detect 45 degree polarised lights in the back, explains that the flashlight polarization direction changes;

3. the control desk program reads the telescopical angle of pitch 8.93 degree and telescopical azimuth 12.46 degree respectively through resolver 5-1; Calculating the angle that half-wave plate need rotate is 10.695 degree; Thereby the generation control signal, and send to electric machine controller 3 (APT direct current machine servo controller TDC001) to control signal;

4. electric machine controller 3 receives control signal; Start the motor 1 rotation half-wave plate 2 among the electric rotating machine assembly PRM1-Z7; And constantly measure the angle of half-wave plates through photoelectric encoder 4; When half-wave plate rotates to its quick shaft direction and basic vector X axle clamp angle is 10.695 just to stop operating when spending, and waits for next bar instruction of real-time controller 4;

5. after half-wave plate is crossed in the flashlight transmission that has changed the polarization direction, on the quantum receiver, be standard with preset basic vector, can detect the angle of polarization is the flashlight of 135 degree.This explained the angle of polarization be the flashlight of 45 degree through passing through half-wave plate again after the rotation change of reflected light path, its polarization angle has become-45 degree, promptly 135 degree with the polarised light negate that records, have just obtained 45 degree polarised lights at the quantum receiving terminal.Automatically regulate with this basic vector of just having accomplished quantum communication system, make the altered flashlight of polarization state can be finally by correct detecting.

Claims (2)

1. basic vector automatic regulating equipment that is used for quantum communication system; It comprises the resolver (5-1) in electric rotating machine assembly (1), half-wave plate (2), electric machine controller (3), real-time controller (4) and the quantum communication system (5), it is characterized in that:

Described electric rotating machine assembly (1) is made up of electric rotating machine, photoelectric encoder and half-wave plate mounting base ,The half-wave plate mounting base is connected with electric rotating machine through worm screw-worm-drive is secondary; The photoelectric encoder of being responsible for measurement electric rotating machine assembly position of rotation is installed on the electric rotating machine; Its precision reaches 0.1 degree, and electric rotating machine adopts controlled direct current machine or stepping motor, and reaction speed is superior to 0.3 second; Electric rotating machine is through the moving half-wave plate mounting base rotation of worm screw-worm-drive subband, and the running accuracy of half-wave plate mounting base is 0.1 degree;

Described resolver (5-1) is two resolvers, is installed in respectively in the quantum communication system (5) on the telescopical pitch axis and trunnion axis, is used to read telescope horizontal azimuth and pitch angle data, and its precision is 0.1 degree;

Electric rotating machine assembly (1) is installed in the quantum communication system (5) in the light path of telescopical back; Half-wave plate (2) is installed on the half-wave plate mounting base in the electric rotating machine assembly (1); Electric machine controller (3) is connected on the electric rotating machine assembly so that read photoelectric encoder data and control electric rotating machine through data wire; Real-time controller (4) connects resolver (5-1) through a data lines and reads telescope Space Angle data, connects electric machine controller (3) through an other data lines and comes to transmit control signal to electric machine controller;

Electric rotating machine assembly (1) records the position of rotation of half-wave plate (2) through photoelectric encoder, and resolver (5-1) records telescopical position of rotation, utilizes real-time controller (4) to read telescopical position in real time through resolver; Go out the angle of flashlight deflection and the angle of half-wave plate needs rotation according to algorithm computation again; Generate control signal and send to electric machine controller (3); Electric machine controller (3) is received the half-wave plate position that records according to photoelectric encoder after the control signal; The control motor rotates to the appropriate location with half-wave plate (2), flashlight is rotated to appropriate polarization state, so that quantum communication system (5) can correctly detect quantum polarisation of light information through basic vector.

2. a kind of basic vector automatic regulating equipment that is used for quantum communication system according to claim 1 is characterized in that: the programming device that described real-time controller (4) adopts computer or has the floating-point operation function.

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