time travelWidely known as a staple of science fiction novels and movies, the phenomenon is at least theoretically possible under certain conditions, including travelling through space at lightning speeds and if the traveller is near a particularly powerful source of electromagnetic radiation. gravity.
But new research suggests that thanks to new innovations in quantum physics, scientists may be moving beyond theory and closer to making time manipulation practical.
Einstein’s theory of relativity helped to show the close relationship between time and space, revealing that the perceived speed of time slows down as a traveler’s speed through space increases. This reality has been demonstrated in experiments involving observed differences in independent clocks, revealing a phenomenon physicists call time dilation.
Technically, when we walk down the street on any day of the week, our feet are moving at a slightly different speed over time than our heads due to the closer proximity of our lower bodies to the Earth’s gravitational field, but these differences are so subtle they’re imperceptible, and these quirks of space and time have little practical meaning.
But recent research from a team at Washington University in St. Louis, in collaboration with collaborators at NIST and the University of Cambridge, is revealing that a new kind of quantum sensor designed to exploit quantum entanglement could lead to a form of real-life time travel detector. The groundbreaking discovery, detailed in a new study published June 27, 2024, raises the bold possibility that scientists may be able to collect data from the past in the near future.
The mysterious world of quantum metrology
In their paper, the team describes experiments using a two-qubit superconducting quantum processor. Measurements demonstrated quantum superiority over any strategy that does not involve the phenomenon of quantum entanglement. Their findings could potentially make it possible to harvest historical data by exploiting the unique properties of what Einstein called “spooky action at a distance.”
While not possible in our everyday world, the realm of quantum physics offers possibilities that defy the conventional rules. Central to this advancement is a property of entangled quantum sensors called “hindsight.”
Cater March, the Charles M. Hohenberg Professor of Physics at the University of Washington and director of the Quantum Leap Center, likens his team’s investigations of these concepts to sending a telescope back in time to capture an image of a shooting star.
From qubits to singlets
The team devised a process in which two quantum particles become entangled in a quantum singlet state, which consists of a pair of qubits whose opposite spins always point in opposite directions, regardless of the reference frame. One of the qubits, which the researchers call the “probe,” is introduced into a magnetic field, inducing it to rotate.
Meanwhile, the qubit that is not exposed to the magnetic field is measured. This reveals a key aspect of the team’s innovation: the entanglement property shared between the two qubits allows the quantum state of the auxiliary qubit to affect the probe qubit under the influence of a magnetic field. A remarkable result is that the probe qubit can be influenced retroactively, effectively facilitating the ability to transmit information “back in time”.
This means that scientists can technically exploit this hindsight phenomenon to determine the optimal direction of a probe qubit’s spin after the fact – as if they were controlling the behavior of the qubit in the past while observing from the future – which can increase the precision of their measurements.
A time-traveling quantum sensor in the real world?
In most cases, measuring the spin rotation of a qubit as a measure of the magnitude of the magnetic field would have a roughly one in three chance of failure, as the alignment of the magnetic field and spin direction would effectively invalidate the result. In contrast, the hindsight property gave the team the unique ability to go back in time and set the optimal direction of the spin.
Under these conditions, the entangled particles effectively act as a single entity that exists simultaneously in both forward and backward positions in time, thereby enabling revolutionary possibilities in the creation of advanced quantum sensors that can produce time-engineered measurements.
The impact of such technology is significant, and could help give rise to all sorts of new sensor technologies, from detecting rare astronomical events to vastly improving how researchers study and manipulate the behavior of magnetic fields.
Ultimately, the team’s new “time travel” technology will be a significant step towards making this well-known science fiction concept a reality, enabling revolutionary new possibilities and insights into the nature of time beyond our current management of time.
“Agnostic Phase EstimationA groundbreaking new study by March and co-authors Xingrui Song, Flavio Salvati, Chandrashekhar Gaikwad, Nicole Junger Halpern and David R.M. Arvidsson-Sukl says: Physics Review Letters.
Micah Hanks is editor-in-chief and co-founder of The Debrief. He can be reached by email. Email: micah@thedebrief.orgHis work micahhanks.com And for X: Micah Hanks.
