It gets better. What if B is also anchored to a quantum object in a superposition of two places? Then the quantum state of A is now blurred in two different ways, depending on the possible positions of B. Since determining the quantum state of B determines the state of A, A and B is now entangled.
In the above example, two quintessential properties of quantum systems – superposition and entanglement – turn out to depend on the reference frame. “The main message is that many of the properties that we consider very important and in some absolute way are relational” or relative, says. Anne-Catherine de la Hamettea co-author of the recent paper.
Even the order of events cannot withstand the strictness of the quantum reference system. For example, from a frame of reference, we can observe that a detector click occurs at a certain time. But from another frame of reference, the click might end up in a superposition that occurs before and after some other event. Whether you observe a click occurring at a particular time or in a superposition of different orders of events depends on the choice of reference system.
A stepping stone to gravity
Researchers hope to use these shifting quantum perspectives to understand the puzzling nature of gravity. Einstein's general theory of relativity, a classical theory of gravity, states that gravity is the warping of the fabric of space-time by a massive object. But how would space-time warp if the object itself were in a superposition of two locations? “That's very difficult to answer using quantum physics and conventional gravity,” said. Victoria Cablea researcher in Brukner's group and co-author of the new paper.
However, switch to a reference frame with the origin in a superposition state and a massive object can end up in a definite position. Now one can calculate its gravitational field. “By finding a convenient quantum frame of reference, we can take a problem that we cannot solve (and turn it) into a problem that we can only use,” Kabel said. known standard physics to solve”.
Such changes of perspective will be useful for analysis future experiments aims to place microscopic masses in superposition. For example, physicists Chiara Marletto And Vlatko Vedral of Oxford University has propose place two masses in a superposition in two locations and then study how this affects their gravitational fields. Growing efforts to formally describe quantum frames of reference may help explain these studies of the interactions between gravity and quantum theory – an essential stepping stone towards a theory of gravity quantum.