Cloud-based quantum computing holds the promise of delivering a quantum advantage, but there are challenges when it comes to detecting qubit entanglement. However, researchers at the Korea Advanced Institute of Science and Technology have made significant progress in this area by developing an innovative solution. Their work, recently published in Intelligent Computing, introduces entanglement witness circuits that enable the detection of entanglement even with limited control over the quantum machine.
Traditionally, researchers need to use a costly procedure known as quantum tomography or rely on entanglement witnesses to determine if a circuit is capable of generating entangled states. Entanglement witnesses are mathematical functions that assess the states of specific qubits and determine whether they are entangled or separable. The challenge arises when direct access to the quantum machine is not available, as is the case with cloud-based quantum computing services like IBMQ and IonQ.
To address this limitation, the team of researchers designed special entanglement witness circuits that leverage the entanglement witness strategy. These circuits enable researchers to detect entanglement using only the measurement statistics provided by the cloud-based quantum computing service. This means that users do not need to have control over qubit allocation, making it easier to satisfy the essential requirement of detecting entangled qubits.
The new entanglement witness circuits build upon the recently developed EW 2.0 framework, which boasts twice the efficiency in detecting entanglement. The researchers describe the detection of entanglement in two- and three-qubit circuits, outline schemes for constructing entanglement witness circuits, and share the results of experiments conducted using IBMQ and IonQ cloud-based quantum computing services.
With this groundbreaking development, cloud-based quantum computing is one step closer to unlocking its true potential. The ability to detect qubit entanglement without direct control over the hardware provides researchers with more flexibility and accessibility in harnessing the power of quantum computation.