A recent study by David Edward Bruschi, S. Chatzinotas deputy head of the research group SIGCOM at the University of Luxembourg, Frank K. Wilhelm from the Saarland University, and Andreas W. Schell from Leibniz University Hannover shows that spacetime can affect the wave packs of coherent light.
Coherent light is a beam of photons having the same frequency and are all in phase. They do not spread and diffuse.
A typical source of coherent light is Laser Light. In Lasers, waves are identical, do not spread, and have the same phase.
We introduce an operational way to distinguish between the overall shift in the pulse wavepacket and its genuine deformation after propagation
They studied the relationship between the pulse of light having quantum coherence and gravity in curved spacetime. They introduced a way to differentiate between the original deformation of the Light pulse after propagation and the overall shift in the wave packet of the pulse. The coherence of light is fundamentally connected to the Quantum coherence of the particles. Quantum coherence is the ability of a quantum system to show interference effects. Coherence in wavefunction is the main reason for the famous double-slit experiment.
We then apply our technique to quantum states of photons that are coherent in the frequency degree of freedom, as well as to states of completely incoherent light
The scientists applied their technique to quantum states of photons that are coherent. Their only focus was Gaussian profile beam and frequency combs, sources of the laser having discrete spectrum and equally spaced frequency lines and they found that the quantum coherence can increase the deformation due to propagation of wave packets of light in curved spacetime.
Read More
Further results of the study hold up to the claim that quantum features like quantum coherence can cause problems in the gravitational properties of a physical system. They used their techniques on Earth to Satellite set up which enables us to test it using current satellite technology, where gravity's effects are much weaker.
Conclusion
Study shows that the deformation induced by propagation in the coherent light pulse or wave packets from a coherent light source having quantum features like quantum coherence is enhanced in the curved background ( curved spacetime). and these quantum features can be used to probe the gravitational properties of a physical system.
These results further support the claim that genuine quantum features, such as quantum coherence, can be used to probe the gravitational properties of physical systems. We specialize our techniques in Earth-to-satellite communication setups, where the effects of gravity are weak but can be tested with current satellite technologies.