Researchers from North Carolina State University and the Massachusetts Institute of Technology have developed a protocol that could revolutionize the field of quantum sensors. By fine-tuning quantum systems to sense signals of interest, designers may be able to create sensors that are much more sensitive than traditional options. This new protocol, designed by Yuan Liu, an assistant professor at NC State, and his colleagues, draws on classical signal processing filter design principles to guide quantum sensors. The researchers coupled a qubit to a bosonic oscillator to manipulate the quantum state of an infinite-dimensional sensor, making it responsive to specific signals. The sensor can then be tuned to a particular target with the help of the qubit, enabling a ‘single-shot’ measurement that provides a quick and clear answer to whether the desired signal is present.
Qubits, the quantum computing equivalent of classical bits, and bosonic oscillators, the quantum counterpart to classical oscillators, play key roles in the protocol developed by Liu and his team. By coupling a qubit to an infinite-dimensional sensor, the researchers were able to simplify the process of manipulating the sensor’s quantum state. This simplification allowed them to focus on a decision question – whether a target has a specific property – rather than trying to quantify the amounts of the target. By employing interferometry to encode the results into the qubit state, the researchers were able to extract a ‘yes’ or ‘no’ answer from the sensor with just a single measurement. This approach represents a significant advancement in quantum sensing, as it provides a clear and efficient way of extracting information from complex systems.
The researchers believe that their protocol could serve as a general framework for designing quantum sensing protocols for a variety of quantum sensors. By utilizing existing quantum resources in leading quantum hardware, such as trapped ions, superconducting platforms, and neutral atoms, in a straightforward manner, the protocol offers a cost-effective and efficient way to detect signals of interest. This non-invasive approach provides an alarm or indicator that a signal is present, eliminating the need for costly repeated measurements. The ability to efficiently extract useful information from infinite-dimensional systems represents a significant step forward in the field of quantum sensing.
The work conducted by Liu and his colleagues was supported by the Army Research Office and the U.S. Department of Energy. The research, published in the journal Quantum, highlights the potential of the new protocol in enhancing the sensitivity and efficiency of quantum sensors. Co-first authors Jasmine Sinanan-Singh and Gabriel Mintzer, graduate students at MIT, contributed to the research, along with Isaac L. Chuang, a professor at MIT. By harnessing the power of quantum sensors and leveraging classical signal processing principles, the researchers have laid the foundation for a new era of quantum sensing that could significantly impact various industries and scientific fields.