Long live the spin

Koichiro Miyanishi, Naoki Ichijo, Makoto Motoyama +3 more

Abstract A solution with hyperpolarized nuclear spins encoded into a long-lived state has been utilized for sensing chemical phenomena. In a conventional way, nuclear spins are hyperpolarized at very low temperatures. In this work, we demonstrate the encoding of a four-nuclear-spin system hyperpolarized at room temperature into a long-lived state in a solution. We apply the solution with the long-lived state as a sensor in ligand-receptor binding experiments.

M. C. Aronson

Christian Bengs

Quantum systems in contact with a thermal environment experience coherent and incoherent dynamics. These drive the system back toward thermal equilibrium after an initial perturbation. The relaxation process involves the reorganization of spin state populations and the decay of spin state coherences. In general, individual populations and coherences may exhibit different relaxation time constants. Particular spin configurations may exhibit exceptionally long relaxation time constants. Such spin configurations are known as long-lived spin order. The existence of long-lived spin order is a direct consequence of the symmetries of the system. For nuclear spin systems, rotational and permutational symmetries are of fundamental importance. Based on the Schur-Weyl duality theorem, we describe a theoretical framework for the study of rotational and permutational dual-symmetries in the context of long-lived spin order. Making use of the proposed formalism, we derive refined bounds on the number on long-lived spin populations and coherences for systems exhibiting rotational-permutational dual-symmetries.

John McKenzie

George Pitcher

T. S. Mahesh, Deepak Khurana

NMR spectroscopy relies on the fact that nuclear spin ensembles in bulk samples under ambient conditions sustain quantum superpositions for durations long enough to implement intricate quantum dynamics. The discovery of long-lived nuclear spin order further enhanced the scope of NMR experiments paving the way for novel applications. In this chapter, we look at the long-lived singlet state (LLSS) from the perspectives of NMR quantum information, wherein the two Zeeman eigenstates of a spin-1/2 nucleus are treated as 0 and 1 states of a quantum bit. In particular, we discuss the following topics: density matrix tomography of the LLSS, initialization of a quantum register via the LLSS, noise spectroscopy of the LLSS, and numerical optimization methods to prepare the LLSS.