Centre for Quantum Technologies

Lu+ optical frequency references with accuracy verified at the 19th digit

Optical atomic frequency references1 have far surpassed their microwave frequency predecessors, leading to an anticipated redefinition of the SI (International System of Units) second2. However, as the scientific community seeks consensus on a new standard, and several state-of-t...

On the complexity of isomorphism problems for tensors, groups, and polynomials III: actions by classical groups

Abstract We study the complexity of isomorphism problems for tensors, represented in coordinates by multiway arrays, under natural actions by classical groups such as orthogonal, unitary, and symplectic groups. These problems arise naturally in statistical data analysis and quant...

In-line fiber-integrated photon-pair generation from van der Waals crystals

Miniaturized quantum light sources that operate directly in optical fibers are an attractive platform for optical quantum technologies. However, most miniaturized spontaneous parametric down-conversion (SPDC) sources still rely on objective-lens-based free-space pumping and colle...

Quantum Pseudorandom Scramblers

Abstract. Quantum pseudorandom state generators ( PRSG s) have stimulated exciting developments in recent years. A PRSG , on a fixed initial (e.g., all-zero) state, produces an output state that is computationally indistinguishable from a Haar random state. However, pseudorandomn...

Cooperative and collective quantum light emission from perovskite superball superstructures

Superfluorescence (SF), the coherent light burst from synchronized quantum emitters, has been demonstrated in perovskite quantum dot superlattices. However, limited control over self-assembly, heterogeneity and emitter properties has hindered systematic exploration of cooperative...

Experimental causal inference from measurements alone in the presence of spatial and temporal quantum correlations

The causal structure of a set of events specifies which events influence which others. Determining this structure, known as causal inference, is a fundamental task in science. Reset-style intervention is commonly used to determine causal structure in classical scenarios. However,...

Ablation removal of transport-blocking defects in surface-electrode ion traps

We demonstrate in situ removal of a transport-blocking defect on a surface-electrode ion trap device using a Q-switched Nd:YAG 532 nm pulsed ablation laser. This approach eliminates the need to vent and rebake the vacuum system, providing a low-overhead defect-remediation techniq...