Single Molecule Detection: Quantum jumps, rotation, switching

Th. Basché, S. Kummer, C. Bräuchle

A. C. J. Brouwer, E. J. J. Groenen, Jan Schmidt

The fluorescence of a single molecule exhibits light and dark periods which reveal the jumping back and forth between the singlet and triplet manifold. In this paper we demonstrate how microwave-induced changes to the distribution of the triplet-residence times can be used to detect magnetic-resonance transitions between triplet sublevels and to determine their kinetics. By synchronizing resonant microwave pulses with the quantum jumps of a terrylene molecule it proved possible to record transient-nutation signals with a high contrast.

Zhao Mu, Yu Zhou, Disheng Chen +5 more

Abstract Optical “blinking” normally refers to a switching behavior of fluorescence for quantum emissions between “ON” and “OFF” state. For quantum dots, single molecules, and nitrogen‐vacancy centers in diamond, it usually stems from conversions between two different charge states, with one emitting strong and bright fluorescence while the other scattering weak or no fluorescence. Here, a different type of blinking from single emitters in ion implanted diamond is reported, with both blinking states exhibiting detectable photoluminescence under nonresonant excitation. Thanks to the low jumping rates, the dynamics of the emission can be directly monitored. The quadratic power dependence of the conversion rates suggests the possibility of two‐photon ionization process in quantum jumps. This work provides extra insights into the photodynamics of the spectral jumps on defect‐based single‐photon emitters hosted in wide‐bandgap semiconductors.

Yuxin Zhao, Wenjie Liang

Erik M. H. P. van Dijk, Jordi Cornet Hernando, L. Kuipers +2 more

Cormac Browne, Tristan Farrow, Oscar Dahlsten +2 more

We demonstrate with an experiment how molecules are a natural test bed for probing fundamental quantum thermodynamics. Single-molecule spectroscopy has undergone transformative change in the past decade with the advent of techniques permitting individual molecules to be distinguished and probed. We demonstrate that the quantum Jarzynski equality for heat is satisfied in this set-up by considering the time-resolved emission spectrum of organic molecules as arising from quantum jumps between states. This relates the heat dissipated into the environment to the free energy difference between the initial and final state. We demonstrate also how utilizing the quantum Jarzynski equality allows for the detection of energy shifts within a molecule, beyond the relative shift.