Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are supremely important techniques with numerous applications in almost all branches of science. However, until recently, NMR methodology was limited by the time constant T1 for the decay of nuclear spin magnetization through contact with the thermal molecular environment. Long-lived states, which are correlated quantum states of multiple nuclei, have decay time constants that may exceed T1 by large factors. Here we demonstrate a nuclear long-lived state comprising two 13C nuclei with a lifetime exceeding one hour in room-temperature solution, which is around 50 times longer than T1. This behavior is well-predicted by a combination of quantum theory, molecular dynamics, and quantum chemistry. Such ultra-long-lived states are expected to be useful for the transport and application of nuclear hyperpolarization, which leads to NMR and MRI signals enhanced by up to five orders of magnitude.

Hyperpolarisation methods that premagnetise agents such as pyruvate are currently receiving significant attention because they produce sensitivity gains that allowd isease tracking and interrogation of cellular metabolism by magnetic resonance.Here,wecommunicate how signal amplification by reversible exchange (SABRE) can providestrong 13 Cpyruvate signal enhancements in seconds through the formation of the novel polarisation transfer catalyst [Ir(H) 2 (h 2 -pyruvate)-(DMSO)(IMes)].B yh arnessing SABRE, strong signals for [1-13 C]-and [2-13 C]pyruvate in addition to along-lived singlet state in the [1,2-13 C 2 ]form are readily created;the latter can be observed five minutes after the initial hyperpolarisation step. We also demonstrate how this development may help with future studies of chemical reactivity.

We report experimental implementation of a protocol for testing the Leggett-Garg inequality (LGI) for nuclear spins precessing in an external magnetic field. The implementation involves certain controlled operations, performed in parallel on pairs of spin-1/2 nuclei (target and probe) from molecules of a nuclear magnetic resonance ensemble, which enable evaluation of temporal correlations from an LG string. Our experiment demonstrates violation of the LGI for time intervals between successive measurements, over which the effects of relaxation on the quantum state of target spin are negligible. Further, it is observed that the temporal correlations decay, and the same target spin appears to display macrorealistic behavior consistent with LGI.

Hyperpolarisation methods that premagnetise agents such as pyruvate are currently receiving significant attention because they produce sensitivity gains that allowd isease tracking and interrogation of cellular metabolism by magnetic resonance.Here,wecommunicate how signal amplification by reversible exchange (SABRE) can providestrong 13 Cpyruvate signal enhancements in seconds through the formation of the novel polarisation transfer catalyst [Ir(H) 2 (h 2 -pyruvate)-(DMSO)(IMes)].B yh arnessing SABRE, strong signals for [1-13 C]-and [2-13 C]pyruvate in addition to along-lived singlet state in the [1,2-13 C 2 ]form are readily created;the latter can be observed five minutes after the initial hyperpolarisation step. We also demonstrate how this development may help with future studies of chemical reactivity.