It’s getting better. What if B is also anchored to a quantum object that is in a superposition of two locations? Then quantum state A is now blurred in two different ways, depending on the possible locations of B. Since the determination of quantum state B determines the state of A, A and B are now entangled.
In the above example, two basic properties of quantum systems – superposition and entanglement – turn out to depend on the reference system. “The main message is that many properties that we think are very important and in some sense absolute are relational” or relative, he said Anne Catherine de la Hametteco-author of the latest article.
Even the order of events is subject to the rigors of quantum reference systems. For example, from one reference frame we can observe a detector click taking place at a specific moment. However, in a different frame of reference, a click may result in a superposition of events preceding and following another event. Whether you observe a click as occurring at a specific moment or as a superposition of different orders of events depends on your choice of frame of reference.
A stepping stone to gravity
Scientists hope to employ these changing quantum perspectives to understand the puzzling nature of gravity. Einstein’s general theory of relativity, which is the classical theory of gravity, says that gravity is the curvature of the structure of space-time by a massive object. But how will space-time curve if the object itself is in a superposition of two locations? “It’s very difficult to answer this question using ordinary quantum physics and gravity,” he said Victoria Cableresearcher from Brukner’s group and co-author of the recent work.
But switch to a reference frame whose origin is in superposition, and the massive object can end up in a specific location. It now becomes possible to calculate its gravitational field. “By finding a convenient quantum reference frame, we can address a problem we cannot solve [and make it] this is a problem that we can simply use standard known physics to solve,” Kabel said.
Such changes in perspective should be useful for analysis future experiments whose purpose is to place very petite masses in a superposition. For example, physicists Chiara Marletto AND Vlatko Vedral from the University of Oxford proposed by placing two masses in a superposition of two locations and then examining how this affects their gravitational fields. Growing attempts to formally describe quantum reference systems may facilitate understand research on the interaction between gravity and quantum theory – a necessary step towards a theory of quantum gravity.