Spin-echo and quantum versus classical critical fluctuations in TmVO${}_4$

Abstract

Using spin-echo Nuclear Magnetic Resonance in the model Transverse-Field Ising system TmVO${}_4$, we show that low frequency quantum fluctuations at the quantum critical point have a very different effect on ${}^{51}$V nuclear-spins than classical low-frequency noise or fluctuations that arise at a finite temperature critical point. Spin-echos filter out the low frequency classical noise but not the quantum fluctuations. This allows us to directly visualize the quantum critical fan and demonstrate the persistence of quantum fluctuations at the critical coupling strength in TmVO${}_4$ to high temperatures in an experiment that remains transparent to finite temperature classical phase transitions. These results show that while dynamical decoupling schemes can be quite effective in eliminating classical noise in a qubit, a quantum critical environment may lead to rapid entanglement and decoherence.

10 pages, 5 figures

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• Quantum criticality
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• Hidden Magnetism and Quantum Criticality in the Heavy Fermion Superconductor CeRhIn5
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Cited by in corpus (5)

• Role of magnetic ions in the thermal Hall effect of the paramagnetic insulator TmVO${}_4$
• Decoherence dynamics in molecular qubits: Exponential, Gaussian and beyond
• Realization of giant elastocaloric cooling at cryogenic temperatures in TmVO${}_4$ via a strain load/unload technique
• Quantum Criticality in the infinite-range Transverse Field Ising Model
• Nuclear magnetic resonance studies in a model transverse field Ising system