Protocol Overcomes Quantum Sensing Decoherence Barrier

In a groundbreaking study, researchers from the University of Southern California (USC) have unveiled a new quantum sensing technique that overcomes the limitations of decoherence, surpassing traditional methods by a wide margin. This innovative technique has the potential to accelerate advancements in various fields, from medical imaging to fundamental physics research.

Decoherence has long been a barrier to the performance of quantum sensors, as it introduces unpredictable behavior due to environmental noise. According to Eli Levenson-Falk, the senior author of the study, decoherence scrambles the state of a quantum system, effectively erasing any quantum sensing signal.

Quantum sensing is known for its exceptional precision in measuring physical quantities, surpassing classical sensors by leveraging properties like superposition, entanglement, and coherence to detect subtle signals that would otherwise be obscured by noise.

Lead author of the study, Malida Hecht, likened quantum sensing to trying to hear a faint whisper in a noisy environment. Quantum sensing devices have the ability to detect minuscule signals that conventional tools would overlook.

In their research, the team tackled the challenge of decoherence by implementing a novel coherence-stabilized protocol in the qubit of their experiment. This protocol, based on theoretical work by co-authors Daniel Lidar and Kumar Saurav, stabilized a key property of the quantum state, significantly enhancing the measurement of small frequency shifts in quantum systems.

The researchers showcased the effectiveness of their protocol on a superconducting qubit, achieving up to 1.65 times better efficacy per measurement compared to the standard Ramsey interferometry protocol. Theoretical analysis suggested potential improvements of up to 1.96 times in certain systems.

According to Levenson-Falk, the experimental demonstration of sensing with a stabilized state highlights the potential for enhancing quantum sensors without the need for complex techniques like real-time feedback or entanglement of multiple sensors. This study underscores the untapped possibilities for improving sensing protocols and their real-world applications.

The study was conducted by Matilda O. Hecht, Kumar Saurav, Evangelos Vlachos, Daniel A. Lidar, and Eli M. Levenson-Falk, all affiliated with USC. Levenson-Falk holds positions as an associate professor of physics and astronomy at USC Dornsife College of Letters, Arts and Sciences, as well as an associate professor of electrical and computer engineering at USC Viterbi School of Engineering.

Daniel Lidar, a Viterbi Professor of Engineering and professor of chemistry, physics, and astronomy at USC, contributed to the theoretical framework of the study. Kumar Saurav, a doctoral student in electrical engineering at USC Viterbi, played a key role in the experimental implementation of the coherence-stabilized protocol. Malida Hecht, a doctoral student in physics at USC Dornsife, provided valuable insights into the quantum sensing applications of the study.