In the physical world, time marches in one direction, but things aren’t so straight forward in the quantum realm.
Researchers have discovered that it’s possible to speed up, slow down, or reverse the flow of time in a quantum system.
In the subatomic universe of quantum physics, you can achieve things considered impossible in our flesh-and-blood physical world. Things like superposition, entanglement, and even teleportation all seem possible when things go quantum. Now, scientists from the Austrian Academy of Sciences (ÖAW) and University of Vienna are adding a kind of time travel to the list.
In a series of papers published throughout the past few years on preprint servers and in various online journals (including Optica, arXiv, and Quantum), researchers including ÖAW’s Miguel Navascués and University of Vienna’s Philip Walther explain the possibility of speeding up, slowing down, and even reversing the flow of time within a quantum system.
Navascués compares the phenomenon to different movie-watching experiences. “In a theater [classical physics], a movie is projected from beginning to end, regardless of what the audience wants,” he explains to the Spanish-language newspaper scientists-prove-particles-in-a-quantum-system-can-be-rejuvenated.html” data-ylk=”slk:El País” class=”link “El País. “But at home [the quantum world], we have a remote control to manipulate the movie. We can rewind to a previous scene or skip several scenes ahead.”
The researchers achieved this by “evolving” a single photon as it passes through a crystal. Using an experimental device called a “quantum switch,” the single photon of light returns to its previous state before it ever makes the journey. In