Time crystal-based optical non-reciprocal information encryption method and device

Abstract

This invention discloses an optical non-reciprocal information encryption method and apparatus based on a time crystal. The method includes the following steps: S1, providing a three-level atomic system containing rubidium atoms, and setting a probe light and a coupling light, wherein the probe light is incident on the atomic system in a fixed direction; S2, controlling the coupling light to propagate collinearly in the opposite direction to the probe light, causing the atomic system to enter a time crystal state and generate a transmission signal with a stable oscillation frequency; S3, acquiring the oscillation frequency of the transmission signal and encoding the oscillation frequency as key information; S4, placing the atomic system in a non-time crystal state, where the transmission signal does not contain the oscillation frequency, thereby achieving non-reciprocal encryption of the key information. This invention causes the atomic system to enter or leave a time crystal state to generate or suppress a transmission signal with a stable oscillation frequency, and encodes and encrypts the oscillation frequency as key information.

Description

Technical Field

[0001] This invention relates to the field of information encryption and anti-counterfeiting technology, specifically to an optical non-reciprocal information encryption method and apparatus based on time crystals. Background Technology

[0002] In the fields of information security and anti-counterfeiting, optical encryption technology has attracted widespread attention due to its ability to modulate information using the properties of light in multiple physical dimensions (such as intensity, polarization, wavelength, phase, and spatial distribution). Traditional optical encryption methods typically rely on static or quasi-static spatial optical patterns (e.g., optical images based on diffraction, interference, or microstructures). While these methods are relatively simple to implement, their information carrier is essentially a fixed spatial intensity or phase distribution. This static characteristic results in a single signal form, making it easy to crack and replicate through high-precision imaging, copying, or reverse engineering. Faced with increasingly complex security threats, its protection level is becoming insufficient.

[0003] To enhance security, researchers have proposed advanced solutions such as dynamic optical patterns, multimodal fusion, and "non-reciprocal" optical responses. The core of non-reciprocal optical encryption lies in making the device's optical response dependent on the incident or observed direction of the light signal. Only under authorized directions will the device present valid information that can be correctly decoded; under unauthorized directions, the output signal appears as meaningless noise or deliberately distorted information, thus physically increasing the difficulty of unauthorized reading. To further enhance practicality, existing technologies also strive to achieve erasable and rewritable information, or combine with other optical modes (such as diffraction) to form multiple verification mechanisms, and even develop foldable three-dimensional encryption structures.

[0004] However, the non-reciprocal encryption schemes of most current systems still rely on the directional dependence of devices in terms of spatial structure or material properties. Their encryption dimension is primarily limited to "space," meaning different "patterns" or "intensities" are observed from different directions. This spatial modulation has limited dynamic update capabilities, and high-order security features (such as time-varying dynamic fingerprints) are difficult to integrate. Faced with application requirements for extremely high security levels (such as core data anti-counterfeiting and dynamic key carriers), the industry urgently needs an encryption mechanism that can achieve high contrast, dynamic switching, and is difficult to counterfeit within the same detection channel in the time or frequency dimensions. An ideal solution should possess the following characteristics: the encryption state can be switched between multiple physical states (such as "oscillating / non-oscillating") through external control parameters (such as light fields); the key carrying the information can be updated in real time without loss; and the encrypted information itself is embedded in the dynamic behavior of the system, rather than in its static structure.

[0005] The concept of "continuous-time crystals" in nonequilibrium physics provides a new approach to addressing these needs. A time crystal refers to a dynamic phase in which a system spontaneously breaks through time-translation symmetry under continuous driving and dissipation conditions, generating stable, continuous periodic oscillations. The characteristics of this oscillation—its "existence," "frequency," "phase," and "spectral structure"—constitute a natural, high-dimensional, dynamic physical resource that is extremely sensitive to initial conditions and parameters, making it highly suitable as an information carrier for physical layer encryption. In particular, studies on systems based on Rydberg state excitations in thermal atomic ensembles (such as room-temperature rubidium atomic vapor) have shown that by cleverly designing the propagation geometry of the light field (e.g., the probe and coupling beams are collinear but propagate in opposite or same directions), the chiral coupling effect induced by atomic thermal motion can be utilized to achieve strong non-reciprocity in dynamic behavior. Under opposite propagation conditions, the system can synchronously enter a stable limiting cycle oscillation (time crystal state); while under same propagation conditions, this oscillation is strongly suppressed. The direction of light propagation thus becomes an efficient and clean "switch," controlling the generation and annihilation of the time crystal state.

[0006] Nevertheless, there is currently no mature, engineered encryption scheme in the technology that directly encodes information into such non-equilibrium dynamic processes. Specifically, there is a lack of practical technology and devices that can reliably switch between "high-contrast oscillation" and "no-oscillation" states by simply switching the propagation direction of a control beam in a fixed detection optical path, and encode and read information in the form of dynamic fingerprints such as oscillation frequency. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, one of the objectives of this invention is to provide an optical non-reciprocal information encryption method based on time crystals. This method controls the propagation direction of the coupling light relative to the probe light to cause the atomic system to enter or leave the time crystal state in order to generate or suppress the transmission signal with a stable oscillation frequency, and encodes and encrypts the oscillation frequency as key information.

[0008] The second objective of this invention is to provide an optical non-reciprocal information encryption device based on a time crystal, which controls the propagation direction of the coupling light relative to the probe light to cause the atomic system to enter or leave the time crystal state to generate or suppress a transmission signal with a stable oscillation frequency, and encodes and encrypts the oscillation frequency as key information.

[0009] To achieve one of the objectives of this invention, the following solution is adopted: An optical non-reciprocal information encryption method based on time crystals includes the following steps: S1. Provide a three-level atomic system containing rubidium atoms, and set a probe light and a coupling light, wherein the probe light is incident on the atomic system in a fixed direction; S2. Control the coupling light to propagate in the opposite direction to the probe light, so that the atomic system enters the time crystal state and generates a transmission signal with a stable oscillation frequency; S3. Obtain the oscillation frequency of the transmitted signal and encode the oscillation frequency as key information; S4. During encryption, the coupling light is controlled to propagate in the same direction and collinearly as the probe light, so that the atomic system is in a non-time crystal state. At this time, the transmitted signal does not contain the oscillation frequency, thereby achieving non-reciprocal encryption of the key information.

[0010] Furthermore, the rubidium atom is 87 Rb atom, the three energy levels include the ground state intermediate state and Ridburg The probe light and coupling light excite the atom from the ground state to the Rydberg state through two-photon resonance excitation.

[0011] Furthermore, the wavelength of the probe light is 780 nm, and the wavelength of the coupling light is 480 nm.

[0012] Furthermore, the oscillation frequency is modulated by adjusting system parameters, including the probe light Rabi frequency. Coupled light Rabi frequency Detecting optical mistuning Optical coupling mistuning At least one of atomic temperature, atomic density, and external magnetic field.

[0013] Furthermore, the key information is composed of a propagation direction sequence and a parameter modulation sequence, forming a multi-parameter coupled key stream.

[0014] To achieve the second objective of this invention, the following solution is adopted: An optical non-reciprocal information encryption device based on a time crystal, used to achieve one of the objectives of the present invention, the optical non-reciprocal information encryption method based on a time crystal, comprising: Atomic unit, containing rubidium atomic gas; A probe light generation and adjustment module is used to generate and adjust the parameters of the probe light and incident it onto the atomic unit in a fixed direction; The coupling light generation and direction switching module is used to generate coupling light and can switch its propagation direction to be collinear with or in the same direction as the probe light. A signal detection module is used to receive and record the detection light signal transmitted from the atomic unit.

[0015] Furthermore, the atomic unit is filled with 87 Saturated vapor chamber of Rb atoms.

[0016] Furthermore, the probe light generation and adjustment module includes a 780nm laser, an optical fiber coupler, a half-wave plate, a polarization beam splitter, and a quarter-wave plate arranged sequentially along the optical path, for adjusting the Rabi frequency and polarization state of the probe light.

[0017] Furthermore, the coupled light generation and direction switching module includes a 480nm laser, an optical fiber coupler, a half-wave plate for adjusting the Rabi frequency, and a polarization beam splitter arranged sequentially along the optical path; the module also includes an optical path steering element for receiving the adjusted coupled light and controllably switching its propagation direction so that it is incident on the atomic unit in the opposite or same direction collinear with the probe light.

[0018] Furthermore, the signal detection module is a photodetector used to monitor the intensity of transmitted light in real time and extract its oscillation frequency components.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention elevates the carrier of information encryption from static spatial patterns to dynamic time-frequency signals, significantly enhancing anti-counterfeiting and anti-cracking capabilities. This invention generates a time-crystalline state by exciting an atomic system and directly uses the spontaneously formed stable oscillation frequency in this state as the key information. This breaks through the limitations of traditional encryption technologies that rely on fixed spatial structures or patterns, encoding information within the system's intrinsic time-domain dynamics. This dynamic key, based on a non-equilibrium physical process, is difficult to replicate externally or obtain through static analysis, fundamentally improving information security.

[0020] 2. This invention utilizes a single control variable to achieve a highly efficient non-reciprocal optical switch, exhibiting high contrast and ease of operation. By changing the propagation direction of the coupling light relative to the fixed probe light, this invention can actively control the atomic system, switching it between a state that generates a definite oscillation frequency and a state that completely suppresses that frequency. This binary control mechanism based on the light propagation direction achieves physical isolation between the "presence" and "absence" of key information within the same probe channel, constituting an essentially optical non-reciprocal response. The mechanism is clear in principle, simple to control, and does not rely on complex spatial structure modulation.

[0021] 3. This invention constructs a stable and easily integrated "fixed probe-dynamic key" encryption architecture. This invention requires that the probe optical path and the signal reading end remain fixed, and the generation and verification of the key rely entirely on the manipulation of the coupling light direction and the dynamic response within the system. This design shifts the core of the encryption function from complex hardware construction to precise control of the physical process, simplifying the system structure and improving stability and reliability, thus laying the technical foundation for the development of practical integrated non-reciprocal encryption devices. Attached Figure Description

[0022] Figure 1 This is a flowchart of the optical non-reciprocal information encryption method based on time crystal in an embodiment of the present invention; Figure 2 This is a schematic diagram of the atomic energy level structure used in the embodiments of the present invention; Figure 3 This is a schematic diagram illustrating the selection and preparation of atomic states in an embodiment of the present invention; Figure 4 This is a frequency domain comparison diagram of the probe light transmission signal under different propagation directions in an embodiment of the present invention; Figure 5 This is a block diagram of the optical non-reciprocal information encryption device based on time crystal in an embodiment of the present invention; Figure 6 This is a schematic diagram of the optical path structure of the experimental device in an embodiment of the present invention. Detailed Implementation

[0023] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0024] Example 1 like Figure 1 As shown, this embodiment of the invention provides an optical non-reciprocal information encryption method based on time crystals, comprising the following steps: S1. Provide a three-level atomic system containing rubidium atoms, and set a probe light and a coupling light, wherein the probe light is incident on the atomic system in a fixed direction.

[0025] S2. Control the coupling light to propagate in the opposite direction to the probe light, so that the atomic system enters the time crystal state and generates a transmission signal with a stable oscillation frequency.

[0026] S3. Obtain the oscillation frequency of the transmitted signal and encode the oscillation frequency as key information.

[0027] S4. During encryption, the coupling light is controlled to propagate in the same direction and collinearly as the probe light, so that the atomic system is in a non-time crystal state. At this time, the transmitted signal does not contain the oscillation frequency, thereby achieving non-reciprocal encryption of the key information.

[0028] The optical non-reciprocal information encryption method based on time crystals according to embodiments of the present invention will be further described in detail below.

[0029] The optical non-reciprocal information encryption method based on time crystal in this embodiment of the invention adopts... 87As a three-level atomic system, Rb atoms are used to prepare high-density Rydberg atoms through two-photon resonance excitation of probe light and coupling light. This makes the internal interactions of the atoms non-negligible, thus providing a physical basis for non-equilibrium dynamic behavior. The following section provides a detailed description of optical non-reciprocal devices based on rubidium atoms and their information encryption methods.

[0030] like Figure 2 As shown, in the energy level structure of this invention, atoms are continuously excited from the ground state to the Rydberg state through a two-photon resonance excitation process. Here, the probe field and the coupling field pass through intermediate states. Excited ground state to Ridburg The precise Zeeman level of a single Rydberg state can be determined selectively by adjusting the polarization states of the probe beam and the coupling beam, such as... Figure 3 As shown. The Rabi frequency and detuning of the probe light and coupling light are denoted as follows: , and , All of the above parameters can be precisely and independently controlled in the experiment.

[0031] The output of the probe beam on the photodetector is recorded as a transmitted signal. Because the realization of Rydberg atoms in hot atomic gases differs significantly from that in cold atomic systems, traditional Rydberg atom measurement schemes based on ionization detection are difficult to apply under these experimental conditions. However, by employing electromagnetically induced transparency (EIT) technology, continuous and dynamic measurements of the probe light signal can be achieved without disrupting the internal quantum states of the atoms, thus providing an experimental basis for observing the behavior of time crystals and their non-reciprocal properties.

[0032] During the limiting ring oscillation phase, a nonlinear coupling occurs between the Rydberg state population and the atomic transition dipole moment, resulting in stable and continuous oscillatory dynamics within the system. Furthermore, the periodic oscillation of the transition dipole moment between the ground and excited states induces a corresponding oscillatory polarization response on the probe transition, and this polarization signal can be directly and in real-time monitored by changes in the transmission of probe light.

[0033] When the coupling light propagating in the same direction is turned off, and only the coupling light propagating in the opposite direction and collinear with the probe light is turned on, the probe light transmission signal corresponding to the highly excited Rydberg state with principal quantum number n=63 is as follows: Figure 4 As shown in (a), the system exhibits a stable and well-coherent periodic oscillation structure. This characteristic indicates that, under suitable system parameter conditions, the system spontaneously enters the limiting ring oscillation phase, i.e., the time-crystal phase. Conversely, when switching to a configuration where the reverse coupling light is turned off and only the co-current collinearly propagating coupling light is turned on, the probe light transmission signal is as follows: Figure 4As shown in (b), its spectral lines are approximately zero against the noise background, and no stable oscillatory structure was observed, indicating that there is no effective Rydberg state excitation in the system at this time, nor is there any limiting loop oscillation behavior.

[0034] The significant difference in dynamic response under the two propagation directions is reflected not only in the contrast between "continuous oscillation" and "no oscillation" in the time domain, but also in the high contrast between the presence and disappearance of the dominant oscillation frequency in the frequency domain: under the condition of reverse collinear propagation, the transmitted signal exhibits a clear and stable dominant frequency peak at non-zero frequencies; while under the condition of co-directional propagation, the dominant frequency is completely suppressed, and its spectrum approximately degenerates into zero-frequency noise background. This achieves near-100% isolation in the frequency domain within the same detection channel, constituting an intrinsic optical non-reciprocal response based on dynamic state.

[0035] Based on the above characteristics, in this invention, the stable limiting cycle oscillation generated by the time crystal state not only manifests as a combination of periodic signals of multiple frequencies, but its oscillation dominance frequency, harmonic structure, and spectral morphology can be continuously modulated according to changes in system control parameters. By jointly adjusting parameters such as the Rabi frequency, detuning amount, atomic temperature, atomic density, or external magnetic field of the probe and coupling light, the system can form distinct sets of oscillation frequencies and frequency domain fingerprints under different parameter combinations. Therefore, this invention encodes information in a key stream composed of "propagation direction + oscillation dominance frequency + multi-parameter modulation rules": different parameter sequences correspond to different dynamic spectral responses, thereby forming a high-dimensional key space coupled with multiple frequencies and multiple parameters. This key stream can be dynamically updated by changing the parameter sequence without any physical reconstruction of the device structure, significantly improving the security and anti-counterfeiting capability of information encryption. Under unauthorized propagation direction, the time crystal oscillation is completely suppressed, and the frequency domain dominance frequency degenerates into a zero-frequency noise background, making the above-mentioned multi-frequency key information unreadable, thereby achieving high-isolation non-reciprocal encryption based on the dynamic frequency domain in the same detection channel.

[0036] The optical non-reciprocal information encryption method based on time crystals in this invention has the following technical effects: 1. The device used in this embodiment of the invention can operate stably at room temperature. Its system configuration and readout method are simple, requiring only the monitoring of a fixed probe light signal. By switching the propagation direction of the coupling light, controllable, phase-change switching between the time-crystal state and the non-time-crystal state can be achieved, forming a highly efficient optical non-reciprocal switch.

[0037] 2. The information in this embodiment of the invention is directly encoded in the oscillation dynamics of the time-domain crystal state (its time-domain waveform and frequency-domain spectral lines constitute a unique fingerprint). By combining the light propagation direction sequence with the external parameter sequence (such as laser parameters, atomic temperature, etc.), a multi-dimensional, dynamic key stream (i.e., a multi-parameter dynamic fingerprint) can be formed, significantly increasing the difficulty of imitation and reverse engineering.

[0038] 3. The encryption key in this embodiment of the invention can be updated in real time and without loss by changing the sequence of external parameters (such as adjusting laser intensity, frequency, etc.), similar to the concept of rewritable dynamic encryption. This feature enables the system to quickly and conveniently reset and recover the key when facing potential security threats, enhancing the long-term security and practicality of the system.

[0039] 4. This invention embeds information in the oscillation frequency of system dynamics, achieving a near 100% contrast non-reciprocal response in the frequency domain. This encryption principle based on dynamic frequency domain characteristics is fundamentally different from traditional optical encryption techniques based on static strength or spatial patterns.

[0040] Example 2 like Figure 5 As shown, this embodiment of the invention also provides an optical non-reciprocal information encryption device based on a time crystal, used to implement the optical non-reciprocal information encryption method based on a time crystal in Embodiment 1, comprising: an atomic unit containing rubidium atomic gas; a probe light generation and adjustment module for generating and adjusting the parameters of the probe light and incident it onto the atomic unit in a fixed direction; a coupling light generation and direction switching module for generating coupling light and being able to switch its propagation direction to be collinear with or in the same direction as the probe light; and a signal detection module for receiving and recording the probe light signal transmitted from the atomic unit.

[0041] Specifically, such as Figure 6 As shown, in the experimental setup, a 780nm laser light is used as the probe light, collimated by an optical fiber coupler, and then passed sequentially through a half-wave plate (HWP) and a polarization beam splitter (PBS) to adjust its Rabi frequency. After adjustment, the linearly polarized light is converted to right-hand circularly polarized light by a quarter-wave plate (QWP). Then, by precisely adjusting the angle of the metal film reflector, the probe light is made to be perpendicularly incident into a saturated vapor chamber with a length of 8 cm, where it interacts with a large number of trapped vapors. 87 Rb atoms interact, and the transmitted signal is ultimately detected by a photodetector. A 480nm laser, used as the coupling light, is also collimated by a fiber coupler and then emitted through a combination of a half-wave plate and a polarization beam splitter (PBS) to achieve the Rabi frequency of the coupling light. Fine-tuning and controllable switching of propagation direction. While keeping the probe beam propagation direction fixed and using it as a reference, two-photon resonance excitation is performed using coupled beams propagating in the opposite and same directions as the probe beam, respectively. By utilizing the velocity selection effect, atoms within a specific velocity range can be selectively excited to the Rydberg state.

[0042] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for encrypting non-reciprocal optical information based on time crystals, characterized in that, Includes the following steps: S1. Provide a three-level atomic system containing rubidium atoms, and set a probe light and a coupling light, wherein the probe light is incident on the atomic system in a fixed direction; S2. Control the coupling light to propagate in the opposite direction to the probe light, so that the atomic system enters the time crystal state and generates a transmission signal with a stable oscillation frequency; S3. Obtain the oscillation frequency of the transmitted signal and encode the oscillation frequency as key information; S4. During encryption, the coupling light is controlled to propagate in the same direction and collinearly as the probe light, so that the atomic system is in a non-time crystal state. At this time, the transmitted signal does not contain the oscillation frequency, thereby achieving non-reciprocal encryption of the key information.

2. The optical non-reciprocal information encryption method based on time crystal according to claim 1, characterized in that, The rubidium atoms are 87 Rb atoms, the three energy levels include the ground state. intermediate state and Ridburg The probe light and coupling light excite the atom from the ground state to the Rydberg state through two-photon resonance excitation.

3. The optical non-reciprocal information encryption method based on time crystal according to claim 2, characterized in that, The wavelength of the probe light is 780 nm, and the wavelength of the coupling light is 480 nm.

4. The optical non-reciprocal information encryption method based on time crystal according to claim 1, characterized in that, The oscillation frequency is modulated by adjusting system parameters, including the probe light Rabi frequency. Coupled light Rabi frequency Detecting optical mistuning Coupled optical detuning At least one of atomic temperature, atomic density, and external magnetic field.

5. The optical non-reciprocal information encryption method based on time crystal according to claim 4, characterized in that, The key information is composed of a propagation direction sequence and a parameter modulation sequence, forming a multi-parameter coupled key stream.

6. A time-crystal-based optical non-reciprocal information encryption device, used to implement the time-crystal-based optical non-reciprocal information encryption method according to any one of claims 1-5, characterized in that, include: Atomic unit, containing rubidium atomic gas; A probe light generation and adjustment module is used to generate and adjust the parameters of the probe light and incident it onto the atomic unit in a fixed direction; The coupling light generation and direction switching module is used to generate coupling light and can switch its propagation direction to be collinear with or in the same direction as the probe light. A signal detection module is used to receive and record the detection light signal transmitted from the atomic unit.

7. The optical non-reciprocal information encryption device based on time crystal according to claim 6, characterized in that, The atomic unit is filled with 87 Saturated vapor chamber of Rb atoms.

8. The optical non-reciprocal information encryption device based on time crystal according to claim 6, characterized in that, The probe light generation and adjustment module includes a 780nm laser, an optical fiber coupler, a half-wave plate, a polarization beam splitter, and a quarter-wave plate arranged sequentially along the optical path, used to adjust the Rabi frequency and polarization state of the probe light.

9. The optical non-reciprocal information encryption device based on time crystal according to claim 6, characterized in that, The coupled light generation and direction switching module includes a 480nm laser, an optical fiber coupler, a half-wave plate for adjusting the Rabi frequency, and a polarization beam splitter arranged sequentially along the optical path; the module also includes an optical path steering element for receiving the adjusted coupled light and controllably switching its propagation direction so that it is incident on the atomic unit in the opposite or same direction as the probe light.

10. The optical non-reciprocal information encryption device based on time crystal according to claim 6, characterized in that, The signal detection module is a photodetector used to monitor the intensity of transmitted light in real time and extract its oscillation frequency components.

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