Phase change amount estimation device

Abstract

A phase change amount estimation device is configured to comprise: a light source (1) that emits light; a quantum switch (2) that outputs the light emitted from the light source (1) to a first light path (11) through which the light passes in the order of the first environmental system (21), the object to be measured (22), and the second environmental system (23), or to a second light path (12) through which the light passes in the order of the second environmental system (23), the object to be measured (22), and the first environmental system (21), on the basis of the quantum state of the light emitted from the light source (1); and a phase change amount estimation unit (3) that estimates, on the basis of the light that has passed through the first optical path (11) or the light that has passed through the second optical path (12), the phase change amount of the light that accompanies the transmission of the measurement object (22).

Description

Technical Field

[0001] The present disclosure relates to a phase change amount estimation device. Background Art

[0002] There is a phase change amount estimation device that estimates the phase change amount of light associated with the transmission of a measurement object or the reflection of the measurement object.

[0003] As such a phase change amount estimation device, Patent Document 1 discloses a device including a light source, an optical branching unit, a phase modulation unit, an optical combining unit, a light intensity measurement unit, and an arithmetic unit.

[0004] The optical branching unit branches the light emitted from the light source into two, outputs one of the branched lights as a reference light to the phase modulation unit, and outputs the other branched light as a signal light to the measurement object. The phase modulation unit performs phase modulation on the reference light output from the optical branching unit. The optical combining unit combines the signal light that has passed through the measurement object and the reference light that has been phase-modulated by the phase modulation unit. The light intensity measurement unit measures the intensity of the light combined by the optical combining unit, that is, the interference light. The arithmetic unit estimates the phase change amount of the signal light associated with the transmission of the measurement object based on the intensity measured by the light intensity measurement unit.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-132838 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The intensity of the light that has passed through the measurement object includes information amount related to the phase change amount of the light, that is, Fisher information amount. The more the Fisher information amount, the higher the estimation accuracy of the phase change amount of the light. The Fisher information amount is determined by, for example, the noise condition of the environmental system through which the light emitted from the light source passes and the interaction time between the light emitted from the light source and the environmental system.

[0010] The phase change amount estimation device disclosed in Patent Document 1 has a problem that it is impossible to increase the Fisher information amount included in the intensity measured by the light intensity measurement unit.

[0011] The present disclosure has been completed to solve the above problems, and an object thereof is to obtain a phase change amount estimation device that can increase the Fisher information amount and improve the estimation accuracy of the phase change amount compared with the phase change amount estimation device disclosed in Patent Document 1.

[0012] Means for Solving the Problems

[0013] The phase change amount estimation device of the present disclosure includes: a light source that emits light; a quantum switch that outputs the light emitted from the light source to a first optical path that passes through the first environmental system, the measurement object, and the second environmental system in this order or a second optical path that passes through the second environmental system, the measurement object, and the first environmental system in this order according to the quantum state of the light emitted from the light source; and a phase change amount estimation unit that estimates the phase change amount of the light accompanying the transmission through the measurement object based on the light that has passed through the first optical path or the light that has passed through the second optical path.

[0014] Advantages of the Invention

[0015] According to the present disclosure, compared with the phase change amount estimation device disclosed in Patent Document 1, the Fisher information amount can be increased, and the estimation accuracy of the phase change amount can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural diagram showing the phase change amount estimation device of Embodiment 1.

[0017] Figure 2 Figure 2 A is an explanatory diagram showing the phenomenon when the quantum state ρ c is |1><1|. Figure 2 B is an explanatory diagram showing the phenomenon when the quantum state ρ c is |0><0|. Figure 2 C is an explanatory diagram showing the superposition of quantum mechanics shown in the order of the channel N1 passing through the quantum state ρ c and the channel N2 passing through the quantum state ρ c .

[0018] Figure 3 is an explanatory diagram showing the estimation principle of the phase change amount based on the Figure 1 phase change amount estimation device shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Hereinafter, in order to explain the present disclosure in more detail, the embodiments for implementing the present disclosure will be described with reference to the drawings.

[0020] Embodiment 1

[0021] Figure 1 is a structural diagram showing the phase change amount estimation device of Embodiment 1.

[0022] Figure 1 The phase change amount estimation device shown includes a light source 1, a quantum switch 2, and a phase change amount estimation unit 3.

[0023] ​​​​The light source 1 is an incoherent light source that emits incoherent light toward the quantum switch 2. As an incoherent light source, for example, there are a lamp light source or an LED (Light Emitting Diode) light source. As the state of incoherent light, for example, there are a single-photon state, a two-level state, or a thermal equilibrium state.

[0024] In Figure 1 In the phase change amount estimation device shown, the light source 1 is an incoherent light source that emits incoherent light. However, this is just an example, and the light source 1 can also be a coherent light source that emits coherent light.

[0025] The quantum switch 2 realizes the superposition of quantum mechanics for the causal order of phenomena.

[0026] Before explaining the specific structure of the quantum switch 2, a brief explanation of the concept of the superposition of quantum mechanics is given.

[0027] Here, it is assumed that Figure 2 the quantum state ρ c .

[0028] The quantum state ρ c is, for example, a two-level system. As a combination of two-level systems, for example, there is a combination of a vacuum state and a single-photon state.

[0029] Figure 2 A is an explanatory diagram showing the phenomenon when the quantum state ρ c is |1><1|. |1><1| represents, for example, a single-photon state.

[0030] In the case where the quantum state ρ c is |1><1|, for example, as Figure 2 shown in A, the quantum state ρ initially passes through the channel N1 and then through the channel N2.

[0031] Figure 2 B is an explanatory diagram showing the phenomenon when the quantum state ρ c is |0><0|. |0><0| represents, for example, a vacuum state.

[0032] In the case where the quantum state ρ c is |0><0|, for example, as Figure 2 shown in B, the quantum state ρ initially passes through the channel N2 and then through the channel N1.

[0033] The quantum switch generates a qubit representing a superposition state where ρ c = |+><+| (refer to Figure 2 C), as a phenomenon formed by superposing Figure 2 the phenomenon shown in A and Figure 2 the phenomenon shown in B. Figure 2C is an explanatory diagram showing the superposition of quantum mechanics in order for the quantum state ρ c to pass through the channel N1 and the quantum state ρ c of the channel N2 respectively.

[0034] By performing the superposition of the quantum state ρ c of quantum mechanics, the quantum state ρ is correlated with the order of the two channels N1 and N2 and the state of the qubit. Therefore, an improvement in the accuracy of quantum measurement can be expected.

[0035] The quantum switch 2 includes an optical splitter 2a, a first mirror 2b, a second mirror 2c, and a third mirror 2d.

[0036] The quantum switch 2 outputs the light emitted from the light source 1 to the first optical path 11 or the second optical path 12 according to the quantum state of the light emitted from the light source 1.

[0037] The first optical path 11 is an optical path through which the light emitted from the light source 1 passes in the order of the first environmental system 21, the measurement object 22, and the second environmental system 23. The first optical path 11 is represented by a solid line in the figure and is a clockwise path.

[0038] The second optical path 12 is an optical path through which the light emitted from the light source 1 passes in the order of the second environmental system 23, the measurement object 22, and the first environmental system 21. The second optical path 12 is represented by a dashed line in the figure and is a counterclockwise path.

[0039] In Figure 1 the phase change amount estimation device shown, the quantum switch 2 outputs the light emitted from the light source 1 to the first optical path 11 or the second optical path 12 according to the quantum state of the light emitted from the light source 1. However, the output destination of the light based on the quantum switch 2 is determined not only according to the quantum state of the light emitted from the light source 1. For example, sometimes it is also determined according to the environmental noise around the quantum switch 2 or the position of the measurement object 22. According to the position of the measurement object 22, for example, whether it is between the first environmental system 21 and the second environmental system 23, or whether it is a position interacting with the two environmental systems, the output destination of the light based on the quantum switch 2 is sometimes different.

[0040] The optical splitter 2a has a beam splitter.

[0041] The optical splitter 2a reflects or transmits the light emitted from the light source 1 according to the quantum state of the light emitted from the light source 1.

[0042] In Figure 1In the phase change amount estimation device shown, an optical demultiplexer 2a reflects the light emitted from a light source 1, and thereby outputs the light to a first optical path 11. The optical demultiplexer 2a transmits the light emitted from the light source 1, and thereby outputs the light to a second optical path 12.

[0043] In addition, the optical demultiplexer 2a outputs the light that has passed through the first optical path 11 or the light that has passed through the second optical path 12 to a phase change amount estimation unit 3.

[0044] In the case where a beam splitter included in the optical demultiplexer 2a is implemented by, for example, a half mirror, the light output from the half mirror to the first optical path 11 appears with a probability of 50%, and the light output from the half mirror to the second optical path 12 appears with a probability of 50%. As a result, the light whose intensity is detected by a first photodetector 3a described later appears with a probability of 50%, and the light whose intensity is detected by a second photodetector 3b described later appears with a probability of 50%.

[0045] The first mirror 2b is implemented by, for example, a total reflection mirror.

[0046] The first mirror 2b is disposed between the optical demultiplexer 2a and a first environmental system 21.

[0047] The first mirror 2b totally reflects the light that has passed through the first optical path 11 or the light that has passed through the second optical path 12.

[0048] The second mirror 2c is implemented by, for example, a total reflection mirror.

[0049] The second mirror 2c is disposed between the first environmental system 21 and a measurement object 22.

[0050] The second mirror 2c totally reflects the light that has passed through the first optical path 11 or the light that has passed through the second optical path 12.

[0051] The third mirror 2d is implemented by, for example, a total reflection mirror.

[0052] The third mirror 2d is disposed between the measurement object 22 and a second environmental system 23.

[0053] The third mirror 2d totally reflects the light that has passed through the first optical path 11 or the light that has passed through the second optical path 12.

[0054] In Figure 1 In the phase change amount estimation device shown, the first mirror 2b, the second mirror 2c, and the third mirror 2d are each implemented by a total reflection mirror. The first mirror 2b, the second mirror 2c, and the third mirror 2d may each be a mirror having a reflectance within a range that is not problematic in practical applications, and are not limited to total reflection mirrors.

[0055] The phase change amount estimation unit 3 includes a first optical detector 3a, a second optical detector 3b, and a change amount estimation processing unit 3c.

[0056] The phase change amount estimation unit 3 estimates the phase change amount of the light accompanying the transmission through the measurement object 22 based on the light that has passed through the first optical path 11 or the light that has passed through the second optical path 12.

[0057] The first optical detector 3a detects the intensity of the light that has passed through the first optical path 11.

[0058] The first optical detector 3a outputs the detection result of the intensity to the change amount estimation processing unit 3c.

[0059] The second optical detector 3b detects the intensity of the light that has passed through the second optical path 12.

[0060] The second optical detector 3b outputs the detection result of the intensity to the change amount estimation processing unit 3c.

[0061] The change amount estimation processing unit 3c is implemented by, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a component formed by combining them.

[0062] The change amount estimation processing unit 3c estimates the phase change amount of the light accompanying the transmission through the measurement object 22 based on the intensity of the light detected by the first optical detector 3a or the intensity of the light detected by the second optical detector 3b.

[0063] The first environmental system 21 is an environmental system included in the middle of the first optical path 11 and the middle of the second optical path 12, respectively.

[0064] The first environmental system 21 is disposed between the first mirror 2b and the second mirror 2c.

[0065] The initial state of the first environmental system 21 is, for example, a thermal equilibrium state at absolute zero.

[0066] The first environmental system 21 may also be an environment that causes energy loss of the light when the light passes through the first environmental system 21. However, since the interaction period between the optical system on the input side of the first environmental system 21 and the first environmental system 21 is very short, the Markov approximation holds between the optical system and the first environmental system 21.

[0067] The measurement object 22 has the property of changing the phase of the light when the light passes through it.

[0068] The second environmental system 23 is an environmental system included in the middle of the first optical path 11 and the middle of the second optical path 12, respectively.

[0069] The second environmental system 23 is arranged between the third mirror 2d and the optical demultiplexer 2a.

[0070] The second environmental system 23 may also be an environment that causes energy loss of light when the light passes through the second environmental system 23.

[0071] The state of the second environmental system 23 may be the same as the state of the first environmental system 21 or different from the state of the first environmental system 21. However, since the interaction period between the optical system on the input side of the second environmental system 23 and the second environmental system 23 is very short, the Markov approximation holds between the optical system and the second environmental system 23.

[0072] Next, the operation of the Figure 1 phase change amount estimation device shown will be described.

[0073] First, the light source 1 emits incoherent light toward the optical demultiplexer 2a of the quantum switch 2.

[0074] The optical demultiplexer 2a reflects the light emitted from the light source 1 or transmits the light emitted from the light source 1.

[0075] The optical demultiplexer 2a reflects the light emitted from the light source 1, thereby outputting the light to the first optical path 11, and transmits the light emitted from the light source 1, thereby outputting the light to the second optical path 12.

[0076] Which optical path among the first optical path 11 and the second optical path 12 the light emitted from the light source 1 is output to by the optical demultiplexer 2a is determined by the quantum state of the light emitted from the light source 1.

[0077] The light output from the optical demultiplexer 2a to the first optical path 11 is totally reflected by the first mirror 2b and reaches the first environmental system 21.

[0078] The light reaching the first environmental system 21, after passing through the first environmental system 21, is totally reflected by the second mirror 2c and reaches the measurement object 22.

[0079] The light reaching the measurement object 22 passes through the measurement object 22. The phase of this light changes when passing through the measurement object 22.

[0080] The light whose phase changes with the passage through the measurement object 22 is totally reflected by the third mirror 2d and reaches the second environmental system 23.

[0081] The light reaching the second environmental system 23, after passing through the second environmental system 23, reaches the optical demultiplexer 2a.

[0082] The optical demultiplexer 2a allows the light that has passed through the second environmental system 23 to pass through, and thereby outputs this light to the first photodetector 3a.

[0083] The light output from the optical demultiplexer 2a to the second optical path 12 reaches the second environmental system 23.

[0084] The light that reaches the second environmental system 23, after passing through the second environmental system 23, is totally reflected by the third mirror 2d and reaches the measurement object 22.

[0085] The light that reaches the measurement object 22 passes through the measurement object 22. The phase of this light changes when passing through the measurement object 22.

[0086] The light whose phase changes as it passes through the measurement object 22 is totally reflected by the second mirror 2c and reaches the first environmental system 21.

[0087] The light that reaches the first environmental system 21, after passing through the first environmental system 21, is totally reflected by the first mirror 2b and reaches the optical demultiplexer 2a.

[0088] The optical demultiplexer 2a allows the light that has been totally reflected by the first mirror 2b to pass through, and thereby outputs this light to the second photodetector 3b.

[0089] The first photodetector 3a detects the intensity of the light that has passed through the first optical path 11, and outputs the detection result of the intensity to the change amount estimation processing unit 3c.

[0090] The second photodetector 3b detects the intensity of the light that has passed through the second optical path 12, and outputs the detection result of the intensity to the change amount estimation processing unit 3c.

[0091] The change amount estimation processing unit 3c estimates the phase change amount of the light associated with the passage of the measurement object 22 based on the intensity of the light detected by the first photodetector 3a or the intensity of the light detected by the second photodetector 3b.

[0092] Next, an explanation will be given of Figure 1 the estimation principle of the phase change amount of the phase change amount estimation device shown.

[0093] Figure 3 is an explanatory diagram showing Figure 1 the estimation principle of the phase change amount of the phase change amount estimation device shown.

[0094] In Figure 3 the input optical system ρ^(hat) Q inis the density operator representing the state of the incoherent light emitted from the light source 1 towards the quantum switch 2. In the text of the specification, it is not possible to mark the "^" symbol above the characters, so it is denoted as ρ^.

[0095] Auxiliary system ρ^ A is the density operator representing the states of the incoherent light emitted from the light source 1, the light after passing through the first optical path 11, and the light after passing through the second optical path 12 respectively. Auxiliary system ρ^ A For example, it is a two-level system. The basis vectors of the respective quantum states in the two-level system are represented by |0 A >, |1 A .

[0096] U^ E 1 is the unitary operator representing the time evolution based on the state of the first environmental system 21, U^ E2 is the unitary operator representing the time evolution based on the state of the second environmental system 23.

[0097] is the unitary operator representing the time evolution based on the state of the object under measurement 22.

[0098] Output optical system ρ^ Q out is the light whose intensity is detected by either the first photodetector 3a or the second photodetector 3b.

[0099] In the case where the basis vector of the quantum state of the auxiliary system ρ^ A is |0 A , the input optical system ρ^ Q in is output to the first optical path 11 by the optical splitter 2a.

[0100] The input optical system ρ^ output to the first optical path 11 Q in interacts with the first environmental system U^ E1 and then, through the object under measurement causes a phase shift

[0101] The input optical system ρ^ after the phase shift Q in interacts with the second environmental system U^ E2 and then becomes the output optical system ρ^ Q out .

[0102] In the case where the basis vector of the quantum state of the auxiliary system ρ^ A is |1 A , the input optical system ρ^Q in Is output by the optical demultiplexer 2a to the second optical path 12.

[0103] The input optical system ρ^ output to the second optical path 12 Q in After interacting with the second environmental system U^ E2 After interacting with the object to be measured, the phase is shifted The phase is shifted

[0104] The input optical system ρ^ after the phase shift Q in After interacting with the first environmental system U^ E1 Becomes the output optical system ρ^ Q out .

[0105] Suppose the initial state of the input optical system ρ^ Q in Is, for example, a superposition of a vacuum state and a two-level system of a single-photon state, and the initial states of the first environmental system U^ E1 And the second environmental system U^ E2 Are each in a thermal equilibrium state at absolute zero. In this case, the interaction time between the input optical system ρ^ Q in And the first environmental system U^ E1 Is very short, and the Markov approximation holds. In addition, the interaction time between the input optical system ρ^ Q in And the second environmental system U^ E2 Is very short, and the Markov approximation holds.

[0106] At this time, the input optical system ρ^ Q in Is expressed as in the following equation (1). In addition, the auxiliary system ρ^ A Is expressed as in the following equation (3). In equation (3), the auxiliary system ρ^ A Is expressed as > as shown.

[0107]

[0108] After the input optical system ρ^ Q in Interacts with the environmental system U^ QEj (j = 1, 2), after being phase-shifted by the object to be measured The optical system after being phase-shifted Is expressed as in the following equation (4).

[0109]

[0110] In Equation (5), is an operator representing the time evolution based on the environmental system E j and is an operator representing the time evolution based on the phase shift. is a notation representing the tensor product.

[0111] The optical system shown in Equation (4) is expressed as in the following Equation (6).

[0112]

[0113] In Equation (6), κ is a constant representing the noise of each of the first environmental system U^ E 1 and the second environmental system U^ E2 respectively, t is the interaction time of the input optical system ρ^ Q in with each of the first environmental system U^ E 1 and the second environmental system U^ E2 respectively. e is the Napier's number and ω is the angular frequency.

[0114] As Figure 2 A or Figure 2 B shows, the output optical system ρ^ Q out when the quantum switch 2 is not used is expressed as in the following Equation (8).

[0115]

[0116] The output optical system ρ^ Q out when the intensity of the light detected by either the first photodetector 3a or the second photodetector 3b is +1 is expressed as in the following Equation (9).

[0117] The output optical system ρ^ Q out when the intensity of the light detected by either the first photodetector 3a or the second photodetector 3b is -1 is expressed as in the following Equation (10).

[0118]

[0119] In Equation (9), P + is the probability when the detection result of detecting +1 as the intensity of the light when the quantum switch 2 is used. Using the quantum switch 2 means performing the projection measurement bases |+><+|.|-><-| on the auxiliary system ρ^ A ​

[0120] In Equation (10), P - is the probability when -1 is detected as the detection result of the light intensity when the quantum switch 2 is utilized.

[0121] In the output optical system ρ^ when the light intensity detected by either the first photodetector 3a or the second photodetector 3b is -1 Q out as shown in Equation (10), it does not contain the information on the amount of phase change of the light accompanied by the transmission of the measurement object of the information.

[0122] The probability of detecting +1 as the detection result of the light intensity is expressed as in the following Equation (11).

[0123] The change amount estimation processing unit 3c obtains the probability shown in Equation (11) as the probability of detecting +1 by either the first photodetector 3a or the second photodetector 3b The constant κ representing noise and the interaction time t are both predetermined values. Therefore, in Equation (11), the only unknown is the amount of phase change Therefore, the change amount estimation processing unit 3c can estimate the amount of phase change from the probability shown in Equation (11)

[0124]

[0125] The Fisher information amount F of the two-level system Q is expressed as in the following Equation (12).

[0126]

[0127] In Equation (13), u, v, and w are respectively the components of the Bloch vector.

[0128] The Bloch vector r shown in Equation (13) is obtained according to the following Equation (14).

[0129]

[0130] In Equation (14), is the Pauli matrix and is expressed as in the following Equation (15).

[0131]

[0132] The output optical system ρ^ shown in Equation (9)Q out The Fisher information quantity F included therein Q can be obtained by means of the Bloch vector r. The output optical system ρ^ shown in Equation (9) Q out The Fisher information quantity F included therein Q is expressed as in the following Equation (16).

[0133]

[0134] The output optical system ρ^ shown in Equation (9) Q out The Fisher information quantity F included therein Q The average value F- of Q is expressed as in the following Equation (22). In the text of the specification, it is impossible to mark the "-" symbol above the character, so it is denoted as F-.

[0135]

[0136] According to the output optical system ρ^ shown in Equation (8) in the case where the unused quantum switch 2 is not used Q out and the Fisher information quantity F of the two-level system shown in Equation (12) Q the Fisher information quantity F0 when the quantum switch 2 is not utilized is expressed as in the following Equation (24).

[0137] The phase change amount estimation device disclosed in Patent Document 1 does not have the quantum switch 2. Therefore, if the noise condition of the environmental system involved in the phase change amount estimation device disclosed in Patent Document 1 and the interaction time between light and the environmental system are respectively the same as the noise condition and the interaction time involved in Equation (8), the Fisher information quantity included in the intensity of the light measured by the light intensity measurement unit disclosed in Patent Document 1 is approximately expressed as in the following Equation (24).

[0138] F0 = e -4κt (24)

[0139] The Fisher information quantity F shown in Equation (22) Q The average value F- of Q is expressed as in the following Equation (25).

[0140]

[0141] Comparing Equation (24) and Equation (25), it can be seen that the Fisher information quantity F in the case where the quantum switch 2 is used Q becomes greater than or equal to the Fisher information quantity F0 in the case where the quantum switch 2 is not used.

[0142] Thus, when the quantum switch 2 is used, the estimation accuracy of the phase change amount is improved compared with the case where the quantum switch 2 is not used.

[0143] When the estimation result of the phase change amount based on Figure 1 the phase change amount estimation device shown is output to an external device, for example, the external device can determine the property of the measurement object 22 based on the estimation result of the phase change amount

[0144] In addition, based on the estimation result of the phase change amount the external device can know whether there is a phase change amount based on the measurement object 22 As a result, the external device can know whether the measurement object 22 exists. Therefore, the phase change amount estimation device shown in Figure 1 can be used as a sensing device.

[0145] In the above Embodiment 1, the phase change amount estimation device is configured to include: a light source 1 that emits light; a quantum switch 2 that outputs the light emitted from the light source 1 to the first optical path 11 that passes through the first environmental system 21, the measurement object 22, and the second environmental system 23 in this order or the second optical path 12 that passes through the second environmental system 23, the measurement object 22, and the first environmental system 21 in this order according to the quantum state of the light emitted from the light source 1; and a phase change amount estimation unit 3 that estimates the phase change amount of the light accompanying the transmission of the measurement object 22 based on the light after passing through the first optical path 11 or the light after passing through the second optical path 12. Therefore, compared with the phase change amount estimation device disclosed in Patent Document 1, the phase change amount estimation device can increase the Fisher information amount and improve the estimation accuracy of the phase change amount.

[0146] In addition, the present disclosure can perform deformation of any structural element of the embodiment or omission of any structural element of the embodiment.

[0147] Industrial Applicability

[0148] The present disclosure is applicable to a phase change amount estimation device.

[0149] Reference Numeral Explanation

[0150] 1: Light source; 2: Quantum switch; 2a: Optical splitter; 2b: First mirror; 2c: Second mirror; 2d: Third mirror; 3: Phase change amount estimation unit; 3a: First photodetector; 3b: Second photodetector; 3c: Change amount estimation processing unit; 11: First optical path; 12: Second optical path; 21: First environmental system; 22: Measurement object; 23: Second environmental system.

Claims

1. A phase change amount estimation device, the phase change amount estimation device having: A light source that emits light; A quantum switch that outputs the light emitted from the light source to a first optical path that passes through the first environmental system, the measurement object, and the second environmental system in this order, or to a second optical path that passes through the second environmental system, the measurement object, and the first environmental system in this order, according to the quantum state of the light emitted from the light source; And A phase change amount estimation unit that estimates the phase change amount of the light accompanying the transmission of the measurement object based on the light that has passed through the first optical path or the light that has passed through the second optical path.

2. The phase change amount estimation device according to claim 1, characterized in that The light source emits incoherent light to the quantum switch.

3. The phase change amount estimation device according to claim 1, characterized in that The quantum switch includes: An optical demultiplexer that outputs the light emitted from the light source to the first optical path or the second optical path according to the quantum state of the light emitted from the light source; A first mirror disposed between the optical demultiplexer and the first environmental system; A second mirror disposed between the first environmental system and the measurement object; And A third mirror disposed between the measurement object and the second environmental system, The optical demultiplexer outputs the light that has passed through the first optical path or the light that has passed through the second optical path to the phase change amount estimation unit.

4. The phase change amount estimation device according to claim 3, characterized in that The optical demultiplexer includes a beam splitter.

5. The phase change amount estimation device according to claim 1, characterized in that The phase change amount estimation unit has: A first photodetector that detects the intensity of the light that has passed through the first optical path; A second photodetector that detects the intensity of the light that has passed through the second optical path; And A change amount estimation processing unit that estimates the phase change amount of the light accompanying the transmission of the measurement object based on the intensity of the light detected by the first photodetector or the intensity of the light detected by the second photodetector.

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