A quantum machine can drastically speed up certain kinds of computation, but only if two or more quantum bits in the machine are entangled—that is, capable of displaying related behavior despite being separated.
Seeking a way for users of cloud-based quantum computing services to detect qubit entanglement, Jiheon Seong and Joonwoo Bae of the Korea Advanced Institute of science and Technology developed and tested an entanglement witness circuit. It works to certify entanglement even when the cloud-based service allows only limited control of the machine. Their research was published in Intelligent Computing.
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