Measurement-Induced Entanglement and Quantum Teleportation on Quantum Processor
Quantum mechanics is pretty weird. It allows a particle to exist in two places at once or be connected to another particle, no matter how far apart they are. But maybe the strangest part is what happens when you actually look at these particles. When you measure a quantum bit, called a qubit, it suddenly stops being in both states at once and “chooses” one. This crossover from the strange quantum world to the regular old classical one is super interesting, and nobody knows exactly how it works.
But over at Google, our team is taking on this mystery. In a paper published in Nature, we talk about an experiment we did using our Sycamore quantum processor with 70 qubits. We found that by changing how strong the measurements were compared to the interactions between qubits, we could cause a kind of “phase transition” in the entanglement of qubits. It’s like how messing with the temperature of water makes it freeze or melt.
The coolest thing we found was “quantum teleportation” – when a quantum state can be transferred from one set of qubits to another. We did all this by coming up with some new ways to do our experiments, and it worked out pretty well. We saw that when we had less noise, the qubits could be affected by residents anywhere in the system. But when there was more noise, only neighbors could cause a change.
This is a big deal, because understanding these measurement-induced effects could help us in the future to build better quantum computers. So, stay tuned!