52 research outputs found
Transmission Spectroscopy of Molecular Spin Ensembles in the Dispersive Regime
The readout in the dispersive regime is originally developed—and it is now largely exploited—for non-demolitive measurement of super- and semiconducting qubits. More recently it has been successfully applied to probe collective spin excitations in ferro(i)magnetic bulk samples or collections of paramagnetic spin centers embedded into microwave cavities. The use of this readout technique within a semiclassical limit of excitation is only marginally investigated although it holds for a wide class of problems, including advanced magnetic resonance techniques. In this work, the coupling between a coplanar microwave resonator and diphenyl-nitroxide organic radical diluted in a fully deuterated benzophenone single crystal is investigated. Two-tone transmission spectroscopy experiments demonstrate the possibility to reconstruct the spectrum of the spin system with little loss of sensitivity with respect to the resonant regime. Likewise, pulse sequences of detuned microwave frequency allow the measurement of the spin-lattice relaxation time (T1). The independent tunability of the probe and the drive power enables one to adjust the signal-to-noise ratio of the spectroscopy. These results suggest that electron spin dispersive spectroscopy can be used as a complementary tool of electron spin resonance to investigate the spin response
Photoswitching of a thermally unswitchable molecular magnet Cu(hfac) 2Li-Pr evidenced by steady-state and time-resolved electron paramagnetic resonance
Most photoswitchable molecular magnets exhibit thermally induced switching, as is typical of spin crossover (SCO), valence tautomerism and SCO-like phenomena. We report a rare case of a copper-nitroxide based molecular magnet Cu(hfac)2Li-Pr that does not exhibit quantitative SCO-like behavior in the temperature range of its chemical stability (2-350 K); however, it can be switched to a metastable thermally inaccessible spin state via visible/near-IR light at cryogenic temperatures. By means of photogeneration, unique information on this otherwise unobservable spin state has been obtained using steady-state Q-band (34 GHz) and time-resolved W-band (94 GHz) electron paramagnetic resonance (EPR) spectroscopy. In particular, we have found that the electronic structure and relaxation properties of the photoinduced state in Cu(hfac)2Li-Pr are very similar to those in its sister compound Cu(hfac)2Ln-Pr that is thermally switchable and has been exhaustively characterized by many analytical methods, previously. The first observation of photoswitchable behavior in a thermally unswitchable copper-nitroxide based molecular magnet Cu(hfac)2Li-Pr paves the way for photoswitching applications of this and similar compounds in the remarkably broad temperature range of 2-350 K. © 2014 American Chemical Society
Self-calibrating Quantum State Tomography
We introduce and experimentally demonstrate a technique for performing
quantum state tomography on multiple-qubit states despite incomplete knowledge
about the unitary operations used to change the measurement basis. Given
unitary operations with unknown rotation angles, our method can be used to
reconstruct the density matrix of the state up to local sigma-z rotations as
well as recover the magnitude of the unknown rotation angle. We demonstrate
high-fidelity self-calibrating tomography on polarization-encoded one- and
two-photon states. The unknown unitary operations are realized in two ways:
using a birefringent polymer sheet---an inexpensive smartphone screen
protector---or alternatively a liquid crystal wave plate with a tuneable
retardance. We explore how our technique may be adapted for quantum state
tomography of systems such as biological molecules where the magnitude and
orientation of the transition dipole moment is not known with high accuracy.Comment: 13 pages, 4 figure
Electronic and Molecular Structures of 1,3,5-Tris(Phenylmethylene)Benzene (S = 3) as Models for Discotic High-Spin Liquid Crystals: Single-Crystal ESR and X-Ray Diffraction Studies
2D-Electron Spin Transient Nutation (2D-ESTN) Study of a Stable High- Spin Carbene (S=3)
Synthesis, electrochemical and spectroscopic studies of highly extended tetraaryl-m-phenylenediamines as precursors of ground-state triplet dications
The Internal Field in a Ferromagnetic Crystal with Chiral Molecular Packing of Achiral Organic Radicals
Organic high-spin systems: synthesis, electrochemical and ETSF studies of a series of tetraaryl-meta-phenylenediamines
Organic high-spin systems of oligoarylamines: Properties of tetraaryl-m-phenylendiamine oligocations as examined by electron transfer stopped-flow method
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