Advances in Squeezed Quantum Multiplets Enable Novel Analysis of -State Superpositions

The behaviour of quantum states under squeezing, a process that reduces uncertainty in one property at the expense of another, forms the basis of a new investigation into complex quantum systems known as squeezed multiplets. Juan Pablo Paz, Corina Révora, and Christian Tomás Schmiegelow explore these unique states, which involve superpositions of multiple photons and exhibit distinct properties compared to standard quantum descriptions. This research establishes a detailed understanding of both ordinary and higher-order squeezed multiplets, revealing surprising similarities and crucial differences in their behaviour. Importantly, the team derives analytical representations of these states in phase space, demonstrating a heightened sensitivity to external disturbances that could prove valuable in developing advanced quantum technologies and sensors.

The research investigates the properties of “squeezed quantum multiplets”, which are sets of mutually orthogonal quantum states created by superposing squeezed states, and extends this concept to include higher-order squeezed states like tri-squeezed and quad-squeezed states. These states involve superpositions of multiple photons, and the study details how ordinary and higher-order multiplets share similarities while exhibiting key differences in their quantum behaviour. Scientists constructed these states using a mathematical framework, allowing for precise control over their quantum properties.

Squeezed Multiplet States for Quantum Precision

The work centres around squeezed states of light, where the uncertainty in one observable is reduced, enhancing precision in measurements. Researchers are investigating multiplet states, created by combining multiple squeezed states, for potential use in quantum information processing and metrology. These states offer hypersensitivity to perturbations, crucial for high-precision sensing. A key achievement is the development of a mathematical description of ordinary squeezed multiplet states, enabling detailed understanding and prediction of their behaviour. The team emphasizes the importance of zeros in the phase-space distribution of these states, relating to their sensitivity and potential for metrology.

Ordinary squeezed multiplets offer similar benefits to more complex higher-order multiplets, but with the advantage of analytical tractability. The research proposes a protocol for experimentally creating these multiplet states using qubits and controlled-squeezing gates, a crucial step towards practical applications. Detailed mathematical analysis in an appendix examines the overlap between two multiplet states under strong squeezing, simplifying expressions to identify key factors determining state behaviour and confirming the location of zeros in phase space. This analysis provides a rigorous foundation for proposed applications in metrology.

Squeezed Multiplets and Higher-Order Quantum States

Scientists have defined and explored the properties of “squeezed multiplets”, sets of mutually orthogonal quantum states created by superposing squeezed states. They extended this concept to include higher-order squeezed states, and detailed how ordinary and higher-order versions share similarities in their quantum behaviour. Experiments revealed that these squeezed multiplets are formed by combining squeezed states along phase-space directions, and that each state is a superposition of states differing in photon number. This characteristic enables the detection of photon loss through parity measurements.

Researchers show that for even numbers of states in a multiplet, two members can represent a single qubit, allowing for the detection of photon losses using super-parity measurements, confirming the robustness of the encoding scheme. Measurements confirm that these squeezed multiplets remain invariant under specific phase-space rotations, dictating which photon number states appear in each multiplet state. The breakthrough delivers analytical expressions for the phase-space distributions of ordinary squeezed multiplets, highlighting their sensitivity to perturbations and suggesting potential applications in precision measurement and quantum technologies.

Squeezed Multiplets and Phase Space Sensitivity

This research defines and investigates “squeezed multiplets”, unique quantum states created by combining squeezed light at multiple angles, and extends this concept to include higher-order variations. The team successfully developed analytical expressions to describe the behaviour of ordinary squeezed multiplets, revealing their properties in phase space. These calculations demonstrate that these states exhibit a notable sensitivity to external disturbances, suggesting potential applications in quantum technologies. The study also explored higher-order squeezed multiplets, finding that while complex, they share key similarities with ordinary squeezed multiplets in their ability to encode quantum information in a way that allows for error detection.

The advantage of using ordinary squeezed multiplets lies in the possibility of complete analytical treatment, enabling precise theoretical predictions. The authors acknowledge that the properties of higher-order squeezed multiplets require numerical investigation, and that some irregular oscillatory behaviour observed in the overlap of certain states requires further study. Future work could focus on fully understanding these oscillations and exploring the practical applications of these highly sensitive states.