Nonlocal quantum macroscopic superposition in a high-thermal low-purity state.

Area of Science:

• Quantum Information Science
• Quantum Optics
• Condensed Matter Physics

Background:

• Quantum state exchange between light and matter is crucial for quantum networks and information processing.
• Macroscopic superposition and nonlocal quantum interactions are of interest for quantum computing and cryptography.
• Previous experiments often require specialized equipment or extreme conditions, limiting practical applications.

Purpose of the Study:

• To demonstrate quantum state exchange principles using conventional equipment and conditions.
• To generate a "quantum teleportation"-like state from a mixed thermal state at room temperature.
• To investigate nonlocal macroscopic superposition and its dependence on second-order correlations.

Main Methods:

• Employed optical coherence tomography (OCT) with a thermal light source at room temperature.
• Induced position uncertainty in the reference arm and used a target with two glass plates in the sample arm.
• Analyzed the chirped signal in the interferogram using fast Fourier transform (FFT) and dual balanced detection.

Main Results:

• Observed a chirped signal whose frequency varied with the medium between glass plates, a nonclassical phenomenon.
• Demonstrated that increasing position uncertainty nonlocally increases position uncertainty via second-order correlations.
• Confirmed the phenomenon is quantum mechanical, relying on two-photon interference and macroscopic superposition in a mixed state.

Conclusions:

• The observed chirping effect cannot be explained by classical physics, supporting quantum mechanical principles.
• Results indicate nonlocal macroscopic superposition occurs through two-photon probability amplitude.
• Macroscopic superposition is achievable with classical thermal sources at room temperature in mixed states.