Quantum secure communication protocol and device based on double-helix structure composite multi-layer encoding

1. A method for secure quantum communication, comprising:

generating a photon;

modulating at least two quantum state dimensions selected from the group consisting of orbital angular momentum (OAM), polarization, and phase of the photon to form a composite quantum state;

directing the photon to an emission point on a helical structure having a defined spatial coordinate corresponding to classical data; and

emitting the photon from the emission point into a quantum channel;

wherein the composite quantum state and spatial coordinate together encode secure information.

2. The method of claim 1 , wherein the helical structure comprises a double-helix geometry defined by a helix radius and pitch, and includes multiple discrete emission points distributed along its surface.

3. The method of claim 1 , wherein the spatial coordinate encodes a classical bit, and wherein the emission point is dynamically selected based on information content.

4. The method of claim 1 , further comprising:

detecting the emitted photon at a receiver;

decoding the classical data from the spatial coordinate of the emission point;

decoding the composite quantum state from at least one of the OAM, polarization, or phase measurement.

5. The method of claim 4 , further comprising applying a classical error correction code to the classical data and a quantum error correction code to quantum data encoded in the composite quantum state.

6. The method of claim 5 , wherein the quantum error correction code comprises a Shor code, a Steane code, or a surface code.

7. The method of claim 5 , wherein the classical error correction code comprises a Reed-Solomon code.

8. The method of claim 1 , wherein emission points are randomized among helical positions to introduce spatial entropy for key distribution protocols.

9. The method of claim 1 , further comprising generating a secure quantum key from two or more photons emitted from emission points of the helical structure for secure communication between a receiver and a sender that includes the helical structure.

10. The method of claim 9 , wherein the secure quantum key is generated according to a quantum key distribution protocol that includes the BB84 quantum key distribution protocol or the E91 quantum key distribution protocol.

11. A quantum communication system, comprising:

a photon source configured to emit single photons;

at least one modulator configured to adjust two or more quantum state dimensions selected from orbital angular momentum (OAM), polarization, and phase;

a helical structure having a plurality of emission points with unique spatial coordinates;

a control module for selecting emission points based on classical data mapping; and

a receiver configured to extract classical and quantum information from received photons.

12. The system of claim 11 , wherein the helical structure is fabricated from a photonic-compatible material selected from the group consisting of silicon nitride, lithium niobate, fused silica, and glass.

13. The system of claim 11 , wherein the control module dynamically adjusts emission point selection according to a pseudorandom sequence synchronized between sender and receiver.

14. The system of claim 11 , wherein quantum key distribution is performed using an extended BB84 protocol combining polarization basis selection and spatial encoding.

15. The system of claim 11 , wherein the receiver includes a spatial decoding module, an OAM mode sorter, a polarization analyzer, and an interferometric phase detector.

16. The system of claim 11 , wherein the helical structure includes multiple parallel helix chains operating as separate quantum channels under a shared control module.

17. The system of claim 11 , wherein each spatial coordinate encodes a classical bit, and wherein the control module is configured to dynamically select an emission point for each photon based on information content.