CN103308189B - Entanglement imaging system and method based on dual-compression coincidence measurements - Google Patents

Abstract

The invention relates to an entanglement imaging system based on dual-compression coincidence measurements. The system comprises a laser, a nonlinear crystal, a narrow-band filter, a beam splitter, a first group of imaging lenses, a second group of imaging lenses, a first spatial light modulator, a second spatial light modulator, a first group of light converging lenses, a second group of light converging lenses, a first point detector, a second point detector, a coincidence measurement circuit and an algorithm module. The laser generates pump light, an entanglement photon pair is produced through nonlinear crystal and is divided into a signal light path and an idle light path after passing through the narrow-band filter to be projected onto the first spatial light modulator and the second spatial light modulator respectively; light is modulated, the modulated light is collected onto the first point detector and the second point detector to be converted into electric signals which are input in the coincidence measurement circuit, and a coincidence measurement value is output; and the algorithm module rebuilds spatial correlation coefficient distribution through a compressive sensing algorithm according to a measurement matrix and the measurement value.

Description

A kind ofly tangle imaging system and method based on two compression coincidence measurement

Technical field

The present invention relates to and tangle light and coincidence measurement field, particularly a kind ofly tangle imaging system and method based on two compression coincidence measurement.

Background technology

Two-photon is tangled normally by Spontaneous Parametric (Spontaneous Parametric Down-Conversion in space, SPDC) under, conversion produces, association between the two-photon position embodying einstein-Podolski-Luo Sen (Einstein-Podolsky-Rosen, EPR) character well or the association between two-photon momentum.To the measurement of one of them photon, just can extrapolate the state of this another photon of photon centering, this characteristic improves the security of communication well.Utilize EPR effect, namely prepare a pair EPR and associate photon pair, communicating pair have determine, constant association, if the polarization state recording one of them photon is upwards, then must be down at the polarization state of another photon of remote position at synchronization, and do not change with the change in space in time, thus, two can be utilized to have and to determine that the light field of incidence relation builds the information carrier of the shared key between communicating pair, any eavesdropping all will destroy this association and be found, and this scheme is exactly famous E91 agreement.Just due to this characteristic, tangling two-photon and having a wide range of applications in quantum key distribution, terrible imaging, quantum calculation, quantum communications.

Experimentally want that the state capturing SPDC is extremely difficult, because the formation efficiency of entangled photon pairs is extremely low, light intensity is extremely weak, the resolution characteristic of detector is also limited, avalanche photodiode arrays is still immature, array scale is also very limited, and the luminous sensitivity of CCD is not high, cannot detect the association of single photon.Thus conventional space is tangled and is measured spatial correlation by mechanical scanning single photon point probe.The region of general scanning 32 × 32 pixels needs 310 days, which greatly limits the development of this research field.

The people such as Dixon propose only to carry out scanning survey to the association on interested region, although do not carry out the measurement of the whole audience, but they also indicate an important attribute of tangling light association, namely no matter be position association or Momentum Correlation, the association distribution that the pixel on detector is right is comparatively sparse.And in recent years by people such as Donoho, Candes, Tao the reconstruction that compressive sensing theory is exactly applicable to sparse signal is proposed, utilize natural sign can under certain base the characteristic of rarefaction representation, only need a small amount of hits (limit far below Nyquist/Shannon's sampling theorem) just perfectly can recover original signal.

Still do not exist in the prior art and utilize the total light intensity of compressed sensing principle to signal light path and idle light path to carry out two compression sampling, set up based on coincidence measurement value and two-way two-value stochastic matrix compressed sensing model so that realize the device of quantum entanglement imaging.

Summary of the invention

The object of the invention is to overcome defect of the prior art, thus provide a kind of and tangle imaging system and method based on two compression coincidence measurement.

To achieve these goals, the invention provides and a kind ofly tangle imaging system based on two compression coincidence measurement, comprise laser instrument 1, nonlinear crystal 2, narrow band pass filter 3, beam splitter 4, first group of imaging len 5-1, second group of imaging len 5-2, first spatial light modulator 6-1, second space photomodulator 6-2, first group assemble receive optical lens 7-1, second group assemble and receive optical lens 7-2, the first point probe 8-1, second point detector 8-2, coincidence measurement circuit 9 and algoritic module 10; Wherein,

Described laser instrument 1 produces pump light, SPDC Entanglement of Formation photon pair is changed under the Spontaneous Parametric of described nonlinear crystal 2, by being divided into signal light path and idle light path by described beam splitter 4 after described narrow band pass filter 3, then project light onto on described first spatial light modulator 6-1 and second space photomodulator 6-2 by described first group of imaging len 5-1, second group of imaging len 5-2 respectively, described first spatial light modulator 6-1 and second space photomodulator 6-2 modulates received light under the control of loaded two-value stochastic matrix, then assemble by described first group and receive optical lens 7-1, assemble receipts optical lens 7-2 for second group and respectively the light after described first spatial light modulator 6-1 and second space photomodulator 6-2 modulation is collected described first point probe 8-1, on second point detector 8-2, by described first point probe 8-1, second point detector 8-2 is transferred to electric signal, the electric signal obtained inputs described coincidence measurement circuit 9, coincidence measurement value is exported by described coincidence measurement circuit 9, last described algoritic module 10 is according to the calculation matrix extrapolated and measured value, compressed sensing algorithm is used to rebuild the distribution of space correlation coefficient.

In technique scheme, the position of described first group of imaging len 5-1, second group of imaging len 5-2 can adjust, make described nonlinear crystal 2 and the first spatial light modulator 6-1 be in respectively described first group of imaging len 5-1 object plane and picture plane on, described nonlinear crystal 2 and second space photomodulator 6-2 be in respectively described second group of imaging len 5-2 object plane and picture plane on, thus can detecting location association character.

In technique scheme, the position of described first group of imaging len 5-1, second group of imaging len 5-2 can adjust, on the object plane making described nonlinear crystal 2 and the first spatial light modulator 6-1 be in described first group of imaging len 5-1 respectively and focal plane, on the object plane that described nonlinear crystal 2 and second space photomodulator 6-2 are in described second group of imaging len 5-2 respectively and focal plane, thus the character of Momentum Correlation can be detected.

In technique scheme, the focal length of described first group of imaging len 5-1, second group of imaging len 5-2 is consistent, and they are identical with the optical path difference of described beam splitter 4; Described first spatial light modulator 6-1 and second space photomodulator 6-2 has identical optical path difference with described beam splitter 4.

In technique scheme, described nonlinear crystal 2 adopts BBO Crystal to realize.

In technique scheme, described first spatial light modulator 6-1, second space photomodulator 6-2 adopt Digital Micromirror Device to realize.

In technique scheme, described first spatial light modulator 6-1, second space photomodulator 6-2 and need synchronous between the first point probe 8-1, second point detector 8-2.

In technique scheme, described first point probe 8-1, second point detector 8-2 adopt in the opto-electronic conversion point probe of large photosensitive area, bucket detector, avalanche diode or photomultiplier any one realize.

In technique scheme, described coincidence measurement circuit 9 adopts double velocity correlation or High order correletion.

In technique scheme, described algoritic module 10 adopts any one algorithm realization compressed sensing following: greedy reconstruction algorithm, Matching pursuitalgorithm MP, orthogonal Matching pursuitalgorithm OMP, base track algorithm BP, LASSO, LARS, GPSR, Bayesian Estimation algorithm, magic, IST, TV, StOMP, CoSaMP, LBI, SP, l1_ls, smp algorithm, SpaRSA algorithm, TwIST algorithm, l ₀reconstruction algorithm, l ₁reconstruction algorithm, l ₂reconstruction algorithm; Sparse base adopt in dct basis, wavelet basis, Fourier transform base, gradient base, gabor transform-based any one.

Present invention also offers one and tangle formation method, comprising:

The step that step 1), Entanglement of Formation photon are right;

Described laser instrument 1 produces pump light, and this pump light changes SPDC Entanglement of Formation photon pair under the Spontaneous Parametric of described nonlinear crystal 2;

Step 2), entangled photon pairs propagate with modulation step;

The entangled photon pairs that step 1) generates is by being divided into signal light path and idle light path by described beam splitter 4 after described narrow band pass filter 3, then project light onto on the first spatial light modulator 6-1 and second space photomodulator 6-2 by described first group of imaging len 5-1, second group of imaging len 5-2 respectively, described first spatial light modulator 6-1 and second space photomodulator 6-2 modulates received light under the control of loaded two-value stochastic matrix;

The step of step 3), compression sampling;

It is described that first group is assembled receipts optical lens 7-1, second group of convergence is received optical lens 7-2 and collected on the first point probe 8-1, second point detector 8-2 by the light after the first spatial light modulator 6-1 and second space photomodulator 6-2 modulation respectively, transferred to electric signal by described first point probe 8-1, second point detector 8-2, the electric signal input coincidence measurement circuit 9 obtained, exports coincidence measurement value by described coincidence measurement circuit 9;

The step of step 4), signal reconstruction.

According to described first spatial light modulator 6-1 and second space photomodulator 6-2, the two-value stochastic matrix when repeatedly overturning obtains calculation matrix to algoritic module 10, obtain measured value according to the coincidence measurement value that described coincidence measurement circuit 9 exports, use compressed sensing algorithm to rebuild space correlation coefficient by described calculation matrix and described measured value and distribute.

In technique scheme, in described step 4), described according to described first spatial light modulator 6-1 and second space photomodulator 6-2, the two-value stochastic matrix when repeatedly overturning obtains calculation matrix and comprises:

Step 4-1), the two-value stochastic matrix that loads when obtaining spatial light modulator repeatedly overturns;

Step 4-2), two-value stochastic matrix is stretched as column vector and row vector respectively;

Step 4-3), obtained column vector is directly multiplied with row vector, calculate calculation matrix.

In technique scheme, in described step 4), the coincidence measurement value exported according to described coincidence measurement circuit 9 obtains measured value and comprises:

Step 4-4), obtain described coincidence measurement circuit 9 export coincidence measurement value;

Step 4-5), be wherein the number of 1 element to being asked respectively by the column vector of two-value stochastic matrix stretching gained and row vector;

Step 4-6), be the number of 1 element by obtained column vector, row vector is that the number of 1 element is multiplied with coincidence measurement value, calculates measured value.

The invention has the advantages that:

The invention provides and a kind ofly tangle imaging system based on two compression coincidence measurement, the right association distribution of the pixel made full use of on detector in conjunction with compressive sensing theory can the priori of sparse expression, can obtain by the two-photon entanglement characteristic changing SPDC generation under Spontaneous Parametric efficiently, compared to common spot scan mode, Measuring Time can be reduced n ²/ log (n) doubly, greatly improve luminous flux simultaneously, each spatial light modulator can collect the total light flux of 1/4, greatly improve image quality, favourable experimental basis is provided for studying space Entanglement further, and according to compressive sensing theory, two-SLM coordinates two point detector to realize two compression samplings of light, more efficiently can also study extensive light signal strength associate feature, in view of these significant advantages, the high and new technology fields such as satellite communication, quantum communications, quantum key distribution can be widely used in.

Accompanying drawing explanation

Fig. 1 is the structural representation tangling imaging system based on two compression coincidence measurement of the present invention in one embodiment.

Drawing explanation

1 laser instrument 2 nonlinear crystal 3 narrow band pass filter

4 beam splitter 5-1 first group imaging len 5-2, second group of imaging len

6-1 first spatial light modulator 6-2 second space photomodulator 7-1 first group assembles and receives optical lens

7-2 second group assembles and receives optical lens 8-1 first point probe 8-2 second point detector

9 coincidence measurement circuit 10 algoritic modules

Embodiment

Now the invention will be further described by reference to the accompanying drawings.

Before the present invention is elaborated, first the related notion in the present invention is described.

Compressed sensing (Compressive Sensing, CS): compressive sensing theory proposes, suppose that signal dimension is N, and this signal is compressible or can rarefaction representation, sampling M < N time (limit far below Nyquist/Shannon's sampling theorem) is then only needed just to solve out definitely by signal by the algorithm of convex optimization, signal just have compressed efficiently by this sample mode while measurement, but measurement itself can not know which element contains important information, but compressed sensing is by minimizing objective function to judge which element contains important information, and its occurrence can be gone out by Exact recovery.First utilize priori, choose suitable sparse base Ψ, it is the most sparse for making wait asking vector x to obtain x ' after Ψ conversion.Be the signal that the k-of N is sparse for length, the scale of M is proportional to klog (N/k).Under the condition of known measurements y, two-value random measurement matrix A and sparse base Ψ, set up mathematical model y=A Ψ x '+e, carry out convex optimization by compressed sensing algorithm, after obtaining x ', then by be finally inversed by x.

Be more than the explanation to the concept in the present invention, below structure of tangling imaging system of the present invention elaborated.

Fig. 1 is in an embodiment, the structural representation tangling imaging system based on two compression coincidence measurement of the present invention, as shown in the figure, this system comprises: optical lens 7-2, the first point probe 8-1, second point detector 8-2, coincidence measurement circuit 9, algoritic module 10 are received in laser instrument 1, nonlinear crystal 2, narrow band pass filter 3, beam splitter 4, first group of imaging len 5-1, second group of imaging len 5-2, the first spatial light modulator 6-1, second space photomodulator 6-2, first group of convergence receipts optical lens 7-1, second group of convergence; Wherein,

Laser instrument 1 produces pump light, SPDC Entanglement of Formation photon pair is changed under the Spontaneous Parametric of nonlinear crystal 2, by being divided into signal light path and idle light path by beam splitter 4 after narrow band pass filter 3, respectively by first group of imaging len 5-1, second group of imaging len 5-2 projects light onto on the first spatial light modulator 6-1 and second space photomodulator 6-2, first spatial light modulator 6-1 and second space photomodulator 6-2 modulates received light under the control of loaded two-value stochastic matrix, then assemble by first group and receive optical lens 7-1, assemble receipts optical lens 7-2 for second group and respectively the light after the first spatial light modulator 6-1 and second space photomodulator 6-2 modulation is collected the first point probe 8-1, on second point detector 8-2, by the first point probe 8-1, second point detector 8-2 is transferred to electric signal, the electric signal input coincidence measurement circuit 9 obtained, coincidence measurement value is exported by coincidence measurement circuit 9, last algorithm module 10 is according to the calculation matrix extrapolated and measured value, compressed sensing algorithm is used to rebuild the distribution of space correlation coefficient.

Below all parts in present system is described further.

Investigate under the pure state of tangling two-photon that parametric down conversion produces may be shifted into Coordinate image, thus location association.In order to the character of detecting location association, adjust the position of first group of imaging len 5-1, second group of imaging len 5-2, make nonlinear crystal 2 and the first spatial light modulator 6-1 be in first group of imaging len 5-1 object plane and picture plane on, nonlinear crystal 2 and second space photomodulator 6-2 be in second group of imaging len 5-2 object plane and picture plane on.

The pure state of tangling two-photon that parametric down conversion produces can be write as the form of momentum eigenstate, and according to principle of conservation of momentum, the incident momentum of light equals the momentum sum of outgoing entangled photon pairs, so must there is Momentum Correlation between entangled photon pairs.In order to detect the character of Momentum Correlation, adjust the position of first group of imaging len 5-1, second group of imaging len 5-2, on the object plane making nonlinear crystal 2 and the first spatial light modulator 6-1 be in first group of imaging len 5-1 and focal plane, on the object plane that nonlinear crystal 2 and second space photomodulator 6-2 are in second group of imaging len 5-2 respectively and focal plane.

The focal length of described first group of imaging len 5-1, second group of imaging len 5-2 is consistent, and they are identical with the optical path difference of beam splitter 4, and described first spatial light modulator 6-1 is also identical with the optical path difference of beam splitter 4 with the optical path difference of second space photomodulator 6-2.

Described nonlinear crystal 2 adopts bbo crystal to realize, BBO and barium metaborate, and its chemical formula is: β-BaB ₂o ₄.

Described first spatial light modulator 6-1, second space photomodulator 6-2 adopt Digital Micromirror Device DMD to realize.Described DMD includes the thousands of array being arranged on the micro mirror on hinge (DMD of main flow is made up of the array of 1024 × 768, maximum can to 2048 × 1152), each micro mirror eyeglass is of a size of 14 μm × 14 μm (or 16 μm × 16 μm), and it can the light of a break-make pixel.These micro mirrors all left floating, by carrying out electronic addressing to the storage unit under each eyeglass with binarization plane signal, just each eyeglass can be allowed to both sides to tilt about 10 ~ 12 ° (in the present embodiment, getting+12 ° and-12 °) for electrostatically, this two states is designated as 1 and 0, corresponding "ON" and "Off" respectively, when eyeglass does not work, they are in " berthing " state of 0 °.

According to the RIP criterion in compressed sensing, the two values matrix of the upper loading of DMD need have randomness, and thus in the present invention, the two values matrix be carried on DMD adopts two-value stochastic matrix, each frame matrix is stretched as a line, as each row element of compressed sensing calculation matrix.Specifically, overturn each time, the two-value stochastic matrix a that the first spatial light modulator 6-1 and second space photomodulator 6-2 loads _iand b _idifferent, and the first spatial light modulator 6-1 and second space photomodulator 6-2 often overturns once, coincidence measurement circuit 9 exports a coincidence measurement value y _i, the measured value in compressed sensing model can be obtained by coincidence measurement value, make Y _i=y _ir _ias i-th measured value, there is one-to-one relationship in i-th row of this i-th measured value and calculation matrix A, wherein, and with stretch during for overturning each time vectorial a _i' and b _i' in be 1 element subscript collection.And i-th row of calculation matrix A required during algoritic module 10 computing can by matrix _i=a _i' b _i' stretching obtains, wherein a _i' be by a _istretch the column vector obtained, b _i' be by b _istretch the row vector obtained; In the process of tangling imaging, described first spatial light modulator 6-1, second space photomodulator 6-2 need upset M time, then to amount to M capable for described calculation matrix A.After obtaining measured value and calculation matrix, just can rebuild the distribution of space correlation coefficient according to compressed sensing algorithm.

Described first spatial light modulator 6-1, second space photomodulator 6-2 and need synchronous between the first point probe 8-1, second point detector 8-2, namely the micro mirror array in the first spatial light modulator 6-1, second space photomodulator 6-2 often overturns once, first point probe 8-1, second point detector 8-2 add up all light intensity of detection arrival in this flip-flop transition in interval, after having overturn, transfer the input of electric signal as coincidence measurement circuit 9 to.

Described first point probe 8-1, second point detector 8-2 can adopt in the opto-electronic conversion point probe of large photosensitive area, bucket detector, avalanche diode or photomultiplier any one realize.

Described algoritic module 10 adopts any one algorithm realization compressed sensing following: greedy reconstruction algorithm, Matching pursuitalgorithm MP, orthogonal Matching pursuitalgorithm OMP, base track algorithm BP, LASSO, LARS, GPSR, Bayesian Estimation algorithm, magic, IST, TV, StOMP, CoSaMP, LBI, SP, l1_ls, smp algorithm, SpaRSA algorithm, TwIST algorithm, l ₀reconstruction algorithm, l ₁reconstruction algorithm, l ₂reconstruction algorithm etc.; Sparse base can adopt dct basis, wavelet basis, Fourier transform base, gradient base, gabor transform-based etc.

Space correlation coefficient to be asked can be double velocity correlation coefficient or High order correletion coefficient, and correspondingly, coincidence measurement circuit 9 need adopt double velocity correlation or High order correletion.

Below in conjunction with the imaging system of tangling in embodiment illustrated in fig. 1, the formation method that tangles of the present invention is described further.

The method comprises the following steps:

The step that step 1), Entanglement of Formation photon are right.

Laser instrument 1 produces pump light, and this pump light changes SPDC Entanglement of Formation photon pair under the Spontaneous Parametric of nonlinear crystal 2.

Step 2), entangled photon pairs propagate with modulation step.

The entangled photon pairs that step 1) generates is by being divided into signal light path and idle light path by beam splitter 4 after narrow band pass filter 3, then project light onto on the first spatial light modulator 6-1 and second space photomodulator 6-2 by first group of imaging len 5-1, second group of imaging len 5-2 respectively, the first spatial light modulator 6-1 and second space photomodulator 6-2 modulates received light under the control of loaded two-value stochastic matrix.

The step of step 3), compression sampling.

First group is assembled receipts optical lens 7-1, second group of convergence is received optical lens 7-2 and collected on the first point probe 8-1, second point detector 8-2 by the light after the first spatial light modulator 6-1 and second space photomodulator 6-2 modulation respectively, transferred to electric signal by the first point probe 8-1, second point detector 8-2, the electric signal input coincidence measurement circuit 9 obtained, exports coincidence measurement value by coincidence measurement circuit 9.

The step of step 4), signal reconstruction.

Algoritic module 10, according to the calculation matrix extrapolated and measured value, uses compressed sensing algorithm to rebuild the distribution of space correlation coefficient.

In step 4), the reckoning of described calculation matrix comprises the following steps:

Step 4-1), the two-value stochastic matrix that loads when obtaining spatial light modulator repeatedly overturns;

Step 4-2), two-value stochastic matrix is stretched as column vector and row vector respectively;

Step 4-3), being directly multiplied with row vector according to obtained column vector calculates calculation matrix.

In order to make the reckoning process of calculation matrix more clear, illustrate below.If the two-value stochastic matrix that the first spatial light modulator 6-1, second space photomodulator 6-2 load is respectively a and b, matrix dimensionality is consistent, be set to m × n, be a row a ' and a line b ' respectively by a and b matrix tensile, dimension becomes t × 1 and 1 × t, wherein t=m × n, the space subscript of two vectorial each elements is one to one.First spatial light modulator 6-1, second space photomodulator 6-2 overturn simultaneously, often overturn once, and coincidence measurement circuit 9 all can record next coincidence measurement value.Stretch when finding out upset each time vectorial a _i' and b _i' in be 1 element subscript collection, be denoted as respectively with if be matrix by the i-th frame of the compressed sensing calculation matrix of these two vector synthesis _i, set the element subscript being designated as 1 equally and integrate as index.In compressed sensing calculates, matrix _isame need are stretched as a line matrix _i', as the i-th row vector in calculation matrix.

Provide an example below, if the two-value stochastic matrix of 3 × 3:

$a_i=\left[\begin{array}{ccc}0& 1& 0\\ 1& 0& 1\\ 0& 0& 0\end{array}\right]$ With $b_i=\left[\begin{array}{ccc}1& 1& 0\\ 1& 0& 0\\ 0& 0& 0\end{array}\right],$ Be stretched as column vector and row vector respectively:

A _i'=[0 1010001 0] ^tand b _i'=[1 1010000 0].

Then $\mathrm{inde}{x}_{a_i^{\&prime;}}=\left[\begin{array}{ccc}2& 4& 8\end{array}\right],\mathrm{inde}{x}_{b_i^{\&prime;}}=\left[\begin{array}{ccc}1& 2& 4\end{array}\right].$

Can be calculated, index=[21 22 24 41 42 44 81 82 84], order matrix _i(index)=1, is

${\mathrm{matrix}}_i=\left[\begin{array}{ccccccccc}0& 0& 0& 0& 0& 0& 0& 0& 0\\ 1& 1& 0& 1& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& 0\\ 1& 1& 0& 1& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& 0\\ 1& 1& 0& 1& 0& 0& 0& 0& 0\\ 0& 0& 0& 0& 0& 0& 0& 0& 0\end{array}\right].$

Analyze from upper example, matrix _i=a _i' b _i'.

In step 4), the coincidence measurement value that described measured value is exported by described coincidence measurement circuit 9.This process comprises the steps:

Step 4-4), obtain described coincidence measurement circuit 9 export coincidence measurement value;

Step 4-5), be wherein the number of 1 element to being asked respectively by the column vector of two-value stochastic matrix stretching gained and row vector;

Step 4-6), be the number of 1 element by obtained column vector, row vector is that the number of 1 element is multiplied with coincidence measurement value, calculates measured value.

Illustrate below.In order to set up the mathematical model of tangling imaging, if unknown quantity is space correlation coefficient x, coincidence measurement value is y, and for spatially any point (u, v), on the first spatial light modulator 6-1, second space photomodulator 6-2, any one light intensity is denoted as then there is double velocity correlation expression formula:

$x(u,v)=\frac{\&lang;\left(a_i(u,v)g_{a_i}(u,v)\right)\left(b_i(u,v)g_{b_i}(u,v)\right)\&rang;}{\&lang;a_i(u,v)g_{a_i}(u,v)\&rang;\&lang;b_i(u,v)g_{b_i}(u,v)\&rang;},$

For the first point probe 8-1, be through a to the first spatial light modulator 6-1 _imodulate total light intensity of coming carry out collection detection.In like manner, second point detector 8-2 is through b to second space photomodulator 6-2 _imodulate total light intensity of coming carry out collection detection, then coincidence measurement circuit 9 carries out coincidence measurement to this to total light intensity value again, and conventional mode is double velocity correlation, obtains y _i.

$y_i=\frac{\&lang;D_{a_i}{D}_{b_i}\&rang;}{\&lang;D_{a_i}\&rang;\&lang;D_{b_i}\&rang;}=\frac{\&lang;x(\mathrm{inde}{x}_{a_i^{\&prime;}},:)g_{a_i}x(:,\mathrm{inde}{x}_{b_i^{\&prime;}})g_{b_i}\&rang;}{\&lang;x(\mathrm{inde}{x}_{a_i^{\&prime;}},:)g_{a_i}\&rang;\&lang;x(:,\mathrm{inde}{x}_{b_i^{\&prime;}})g_{b_i}\&rang;}$

$=\frac{\&lang;(a_i(1,:)g_{a_i}(1,:)+a_i(2,:)g_{a_i}(2,:)+\&CenterDot;\&CenterDot;\&CenterDot;)\&CenterDot;(b_i(:,1)g_{b_i}(:,1)+b_i(:,2)g_{b_i}(:,2)+\&CenterDot;\&CenterDot;\&CenterDot;)\&rang;}{\&lang;(a_i(1,:)+a_i(2,:)+\&CenterDot;\&CenterDot;\&CenterDot;)\&rang;\&lang;b_i(:,1)+b_i(:,2)+\&CenterDot;\&CenterDot;\&CenterDot;\&rang;}$

$=\frac{\&lang;a_i\left(\mathrm{1,1}\right)g_{a_i}\left(\mathrm{1,1}\right)b_i\left(\mathrm{1,1}\right)g_{b_i}\left(\mathrm{1,1}\right)+a_i\left(\mathrm{1,2}\right)g_{a_i}\left(\mathrm{1,2}\right)b_i\left(\mathrm{1,2}\right)g_{b_i}\left(\mathrm{1,2}\right)+a_i\left(\mathrm{2,1}\right)g_{a_i}\left(\mathrm{2,1}\right)b_i\left(\mathrm{2,1}\right)g_{b_i}\left(\mathrm{2,1}\right)+\&CenterDot;\&CenterDot;\&CenterDot;\&rang;}{\&lang;(a_i(1,:)\backslash +a_i(2,:)+\&CenterDot;\&CenterDot;\&CenterDot;)\&rang;\&lang;b_i(:,1)+b_i(:,2)+\&CenterDot;\&CenterDot;\&CenterDot;\&rang;}$

$\&ap;\frac{\&lang;a_i\left(\mathrm{1,1}\right)g_{a_i}\left(\mathrm{1,1}\right)b_i\left(\mathrm{1,1}\right)g_{b_i}\left(\mathrm{1,1}\right)\&rang;+\&lang;a_i\left(\mathrm{1,2}\right)g_{a_i}\left(\mathrm{1,2}\right)b_i\left(\mathrm{1,2}\right)g_{b_i}\left(\mathrm{1,2}\right)\&rang;+\&lang;a_i\left(\mathrm{2,1}\right)g_{a_i}\left(\mathrm{2,1}\right)b_i\left(\mathrm{2,1}\right)g_{b_i}\left(\mathrm{2,1}\right)\&rang;+\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{sum}(\mathrm{inde}{x}_{a_i^{\&prime;}})\&lang;a_i(u,v)g_{a_i}(u,v)\&rang;\mathrm{sum}\left(\mathrm{inde}{x}_{b_i^{\&prime;}}\right)\&lang;b_i(u,v)g_{b_i}(u,v)\&rang;}$

$=\frac{1}{\mathrm{sum}\left(\mathrm{inde}{x}_{a_i^{\&prime;}}\right)\mathrm{sum}\left(\mathrm{inde}{x}_{b_i^{\&prime;}}\right)}{a}_i^{\&prime;}{b}_i^{\&prime;}x$

$=\frac{\mathrm{matri}{x}_{i}x}{r_i}$

Wherein, make measured value Y _i=y _ir _imeasured value can be obtained.

After obtaining calculation matrix A and measured value Y, the mathematical model of tangling imaging becomes: Y=Ax+e, and x is wherein the column vector after stretching, and e represents noise, in sampling process, certainly exist system noise, described system noise mainly comprises optical noise and electrical noise.Because calculation matrix A and measured value Y is given value, utilizing compressive sensing theory algorithm just perfection to recover to wait to ask unknown column vector x, x is lined up the matrix of m × n by column weight, is space correlation coefficient distribution X.

The present invention utilizes twice space compression (to refer to that the first spatial light modulator 6-1 is to light Stochastic Modulation, first point probe 8-1 carries out the process of sub-sampling to the total light intensity after modulation, and second space photomodulator 6-2 is to light Stochastic Modulation, second point detector 8-2 carries out the process of sub-sampling to the total light intensity after modulation), greatly reduce Measuring Time.For the space distribution of a n-pixel length, conventional spot scan system needs at least to sample n ²secondary, and compression sampling, only need the secondary measurement of nlog (n), and the spot scan of routine, total luminous flux is evenly distributed to and accepts in plane, transfer point detector, also can only detect the light intensity of a pixel at every turn, originally two-photon is tangled just lower to production rate, dividing equally of outer luminous flux in addition, the signal be actually detected will be extremely weak, and the imaging system of tangling based on two compression coincidence measurement provided by the present invention, overcome this shortcoming well, for each spatial light modulator, 1/4 of about total light flux can be collected, this will bring splendid image quality, obtain and better rebuild, efficiency will be measured and improve n ²/ log (n) doubly.

It should be noted last that, above embodiment is only in order to illustrate technical scheme of the present invention and unrestricted.Although with reference to embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, modify to technical scheme of the present invention or equivalent replacement, do not depart from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (13)

1. one kind is tangled imaging system based on two compression coincidence measurement, it is characterized in that, comprise laser instrument (1), nonlinear crystal (2), narrow band pass filter (3), beam splitter (4), first group of imaging len (5-1), second group of imaging len (5-2), first spatial light modulator (6-1), second space photomodulator (6-2), assemble for first group and receive optical lens (7-1), assemble for second group and receive optical lens (7-2), first point probe (8-1), second point detector (8-2), coincidence measurement circuit (9) and algoritic module (10), wherein,

Described laser instrument (1) produces pump light, SPDC Entanglement of Formation photon pair is changed under the Spontaneous Parametric of described nonlinear crystal (2), by being divided into signal light path and idle light path by described beam splitter (4) after described narrow band pass filter (3), then project light onto on described first spatial light modulator (6-1) and second space photomodulator (6-2) by described first group of imaging len (5-1), second group of imaging len (5-2) respectively, described first spatial light modulator (6-1) and second space photomodulator (6-2) are modulated received light under the control of loaded two-value stochastic matrix, then assemble by described first group and receive optical lens (7-1), assemble receipts optical lens (7-2) for second group and respectively the light after described first spatial light modulator (6-1) and second space photomodulator (6-2) modulation is collected described first point probe (8-1), on second point detector (8-2), by described first point probe (8-1), second point detector (8-2) is transferred to electric signal, the electric signal obtained inputs described coincidence measurement circuit (9), coincidence measurement value is exported by described coincidence measurement circuit (9), last described algoritic module (10) is according to the calculation matrix extrapolated and measured value, compressed sensing algorithm is used to rebuild the distribution of space correlation coefficient.

2. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described first group of imaging len (5-1), the position of second group of imaging len (5-2) can adjust, make described nonlinear crystal (2) and the first spatial light modulator (6-1) be in respectively described first group of imaging len (5-1) object plane and picture plane on, described nonlinear crystal (2) and second space photomodulator (6-2) be in respectively described second group of imaging len (5-2) object plane and picture plane on, thus can detecting location association character.

3. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described first group of imaging len (5-1), the position of second group of imaging len (5-2) can adjust, on the object plane making described nonlinear crystal (2) and the first spatial light modulator (6-1) be in described first group of imaging len (5-1) respectively and focal plane, on the object plane that described nonlinear crystal (2) and second space photomodulator (6-2) are in described second group of imaging len (5-2) respectively and focal plane, thus the character of Momentum Correlation can be detected.

4. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, the focal length of described first group of imaging len (5-1), second group of imaging len (5-2) is consistent, and they are identical with the optical path difference of described beam splitter (4); Described first spatial light modulator (6-1) and second space photomodulator (6-2) have identical optical path difference with described beam splitter (4).

5. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described nonlinear crystal (2) adopts BBO Crystal to realize.

6. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described first spatial light modulator (6-1), second space photomodulator (6-2) adopt Digital Micromirror Device to realize.

7. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, need synchronous between described first spatial light modulator (6-1), second space photomodulator (6-2) and the first point probe (8-1), second point detector (8-2).

8. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described first point probe (8-1), second point detector (8-2) adopt in the opto-electronic conversion point probe of large photosensitive area, bucket detector, avalanche diode or photomultiplier any one realize.

9. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described coincidence measurement circuit (9) adopts double velocity correlation or High order correletion.

10. according to claim 1ly tangle imaging system based on two compression coincidence measurement, it is characterized in that, described algoritic module (10) adopts any one algorithm realization compressed sensing following: greedy reconstruction algorithm, Matching pursuitalgorithm MP, orthogonal Matching pursuitalgorithm OMP, base track algorithm BP, LASSO, LARS, GPSR, Bayesian Estimation algorithm, magic, IST, TV, StOMP, CoSaMP, LBI, SP, l1_ls, smp algorithm, SpaRSA algorithm, TwIST algorithm, l ₀reconstruction algorithm, l ₁reconstruction algorithm, l ₂reconstruction algorithm; Sparse base adopt in dct basis, wavelet basis, Fourier transform base, gradient base, gabor transform-based any one.

11. based on one of claim 1-10 Suo Shu based on two compression coincidence measurement tangle that imaging system realizes tangle formation method, comprising:

Step 1), the right step of Entanglement of Formation photon;

Described laser instrument (1) produces pump light, and this pump light changes SPDC Entanglement of Formation photon pair under the Spontaneous Parametric of described nonlinear crystal (2);

Step 2), entangled photon pairs propagate with modulation step;

Step 1) entangled photon pairs that generates is by being divided into signal light path and idle light path by described beam splitter (4) after described narrow band pass filter (3), then project light onto on the first spatial light modulator (6-1) and second space photomodulator (6-2) by described first group of imaging len (5-1), second group of imaging len (5-2) respectively, described first spatial light modulator (6-1) and second space photomodulator (6-2) are modulated received light under the control of loaded two-value stochastic matrix;

Step 3), the step of compression sampling;

It is described that first group is assembled receipts optical lens (7-1), second group of convergence is received optical lens (7-2) and collected on the first point probe (8-1), second point detector (8-2) by the light after the first spatial light modulator (6-1) and second space photomodulator (6-2) modulation respectively, transferred to electric signal by described first point probe (8-1), second point detector (8-2), electric signal input coincidence measurement circuit (9) obtained, exports coincidence measurement value by described coincidence measurement circuit (9);

Step 4), the step of signal reconstruction;

According to described first spatial light modulator (6-1) and second space photomodulator (6-2), the two-value stochastic matrix when repeatedly overturning obtains calculation matrix to algoritic module (10), obtain measured value according to the coincidence measurement value that described coincidence measurement circuit (9) exports, use compressed sensing algorithm to rebuild space correlation coefficient by described calculation matrix and described measured value and distribute.

12. according to claim 11ly tangle formation method, it is characterized in that, in described step 4) in, it is described that according to described first spatial light modulator (6-1) and second space photomodulator (6-2), the two-value stochastic matrix when repeatedly overturning obtains calculation matrix and comprises:

Step 4-1), the two-value stochastic matrix that loads when obtaining spatial light modulator repeatedly overturns;

Step 4-2), two-value stochastic matrix is stretched as column vector and row vector respectively;

Step 4-3), obtained column vector is directly multiplied with row vector, calculate calculation matrix.

13. according to claim 12ly tangle formation method, it is characterized in that, in described step 4) in, the coincidence measurement value exported according to described coincidence measurement circuit (9) obtains measured value and comprises:

Step 4-4), obtain the coincidence measurement value that described coincidence measurement circuit (9) exports;

Step 4-5), be wherein the number of 1 element to being asked respectively by the column vector of two-value stochastic matrix stretching gained and row vector;

Step 4-6), be the number of 1 element by obtained column vector, row vector is that the number of 1 element is multiplied with coincidence measurement value, calculates measured value.