Nian Y-H, Vinograd I, Green T, Chaffey C, Massat P, Singh R R P, Zic M P, Fisher I R, Curro N J
Department of Physics and Astronomy, University of California Davis, Davis, California, USA.
Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University, California 94305, USA.
Phys Rev Lett. 2024 May 24;132(21):216502. doi: 10.1103/PhysRevLett.132.216502.
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 echoes 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.
在模型横向场伊辛系统TmVO₄中使用自旋回波核磁共振，我们表明，量子临界点处的低频量子涨落对⁵¹V核自旋的影响与经典低频噪声或在有限温度临界点出现的涨落有很大不同。自旋回波滤除了低频经典噪声，但没有滤除量子涨落。这使我们能够直接可视化量子临界扇，并在对有限温度经典相变保持透明的实验中，证明TmVO₄中临界耦合强度下的量子涨落持续到高温。这些结果表明，虽然动态解耦方案在消除量子比特中的经典噪声方面可能非常有效，但量子临界环境可能导致快速纠缠和退相干。
