541 research outputs found
YBCO microwave resonators for strong collective coupling with spin ensembles
Coplanar microwave resonators made of 330 nm-thick superconducting YBCO have
been realized and characterized in a wide temperature (, 2-100 K) and
magnetic field (, 0-7 T) range. The quality factor exceeds 10
below 55 K and it slightly decreases for increasing fields, remaining 90 of
for T and K. These features allow the coherent coupling
of resonant photons with a spin ensemble at finite temperature and magnetic
field. To demonstrate this, collective strong coupling was achieved by using
DPPH organic radical placed at the magnetic antinode of the fundamental mode:
the in-plane magnetic field is used to tune the spin frequency gap splitting
across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings
are observed with a splitting as large as MHz at K. The
spin-cavity collective coupling rate is shown to scale as the square root of
the number of active spins in the ensemble.Comment: to appear in Appl. Phys. Let
Quantum Computation with Molecular Nanomagnets: Achievements, Challenges, and New Trends
Molecular nanomagnets exhibit quanto-mechanical properties that can be nicely tailored at synthetic level: superposition and entanglement of quantum states can be created with molecular spins whose manipulation can be done in a timescale shorter than their decoherence time, if the molecular environment is controlled in a proper way. The challenge of quantum computation is to exploit the similarities between the coherent manipulation of molecular spins and algorithms used to process data and solve problems. In this chapter we shall firstly introduce basic concepts, stressing analogies between the physics and the chemistry of molecular nanomagnets and the science of computing. Then we shall review main achievements obtained in the first decade of this field and present challenges for the next future. In particular we shall focus on two emerging topics: quantum simulators and hybrid systems made by resonant cavities and molecular nanomagnets.Molecular nanomagnets exhibit quanto-mechanical properties that can be nicely tailored at synthetic level: superposition and entanglement of quantum states can be created with molecular spins whose manipulation can be done in a timescale shorter than their decoherence time, if the molecular environment is controlled in a proper way. The challenge of quantum computation is to exploit the similarities between the coherent manipulation of molecular spins and algorithms used to process data and solve problems. In this chapter we shall firstly introduce basic concepts, stressing analogies between the physics and the chemistry of molecular nanomagnets and the science of computing. Then we shall review main achievements obtained in the first decade of this field and present challenges for the next future. In particular we shall focus on two emerging topics: quantum simulators and hybrid systems made by resonant cavities and molecular nanomagnets
Spin-enhanced magnetocaloric effect in molecular nanomagnets
An unusually large magnetocaloric effect for the temperature region below 10 K is found for the Fe-14 molecular nanomagnet. This is to large extent caused by its extremely large spin S ground state combined with an excess of entropy arising from the presence of low-lying excited S states. We also show that the highly symmetric Fe-14 cluster core, resulting in small cluster magnetic anisotropy, enables the occurrence of long-range antiferromagnetic order below T-N=1.87 K
Microwave photon detectors based on semiconducting double quantum dots
Detectors of microwave photons find applications in different fields ranging from security to cosmology. Due to the intrinsic difficulties related to the detection of vanishingly small energy quanta ¯hω, significant portions of the microwave electromagnetic spectrum are still uncovered by suitable techniques. No prevailing technology has clearly emerged yet, although different solutions have been tested in different contexts. Here, we focus on semiconductor quantum dots, which feature wide tunability by external gate voltages and scalability for large architectures. We discuss possible pathways for the development of microwave photon detectors based on photon-assisted tunneling in semiconducting double quantum dot circuits. In particular, we consider implementations based on either broadband transmission lines or resonant cavities, and we discuss how developments in charge sensing techniques and hybrid architectures may be beneficial for the development of efficient photon detectors in the microwave range
Coherent coupling of molecular spins with microwave photons in planar superconducting resonators
Within the quest for solid state quantum systems to be
used for fundamental as well as applied research, molecular
spins have recently emerged as a versatile platform with
interesting performances in terms of quantum coherence and
correlation. Molecular units provide well defined environment
to electronic spins and they represent elementary bricks for
complex nano-architectures and nano-devices. Here we review
our recent efforts and results on their efficient integration in
circuit Quantum ElectroDynamics and, more specifically, in
reaching their coherent coupling with microwave photons in
planar resonators. To monitor molecular spin performances
over a wide temperature and magnetic field range we have
first developed microwave planar resonators made of high
Tc superconductors, obtaining excellent performances up
to liquid Nitrogen temperature and in magnetic fields up to
7 Tesla. Ensembles of different molecular spins systems are
then systematically tested. The regime of high spin-photon
cooperativity is achieved with molecular spins diluted in nonmagnetic
matrix at 0.5 K, while the strong coupling regime is
observed with concentrated samples of organic radicals up to
50 K. The possibility to create coherent states among distinct
spin ensembles is further explored in similar spectroscopic
experiments. These results show that molecular spins can be
efficiently integrated in quantum devices
Universal Screening for Congenital CMV Infection
Congenital cytomegalovirus (CMV) infection is an important public health problem. It is a leading cause of disability in children. Congenitally infected neonates often appear asymptomatic at birth or have nonspecific symptoms. An early diagnosis and subsequent early antiviral therapy associated to nonpharmacological therapy (e.g., hearing rehabilitation, speech-language therapy, and cochlear implants) can reduce long-term disability. Much research has been done in this field, but further studies are still necessary. Looking back at the most recent papers, we will draw a review on this topic trying to answer to the question: could universal CMV screening be a useful and cost-effective diagnostic tool
Molecular Spins in the Context of Quantum Technologies
Molecular spins have shown interesting quantum features which make them potential candidates for the implementation of quantum information processing. New challenges related to possible applications in broader class of quantum technologies are currently under discussion. Here, we revisit some key features trying to learn something from experiences in near fields
Quantum sensing of magnetic fields with molecular spins
Spins are prototypical systems with the potential to probe magnetic fields down to the atomic scale limit. Exploiting their quantum nature through appropriate sensing protocols allows to enlarge their applicability to fields not always accessible by classical sensors. Here we first show that quantum sensing protocols for AC magnetic fields can be implemented with molecular spin ensembles embedded into hybrid quantum circuits. We then show that, using only echo detection at microwave frequency and no optical readout, Dynamical Decoupling protocols synchronized with the AC magnetic fields can enhance sensitivity up to S ≈ 10^(−10) − 10^(−9) T Hz^(−1/2) with a low (4-5) number of applied pulses. These results paves the way for the development of strategies to exploit molecular spins as quantum sensors
LO STILE DAL PUNTO DI VISTA DELLA LINGUISTICA DEL TESTO. TRADUZIONE DI TREDICI SAGGI TRATTI DAL VOLUME “PERSPEKTIVEN AUF STIL” (2001) A CURA DI EVA-MARIA JAKOBS E ANNELY ROTHKEGEL.
Traduzione e commento di testi di autori che hanno elaborato nuove teorie stilistiche
Microwave dual-mode resonators for coherent spin-photon coupling
We implement superconducting Yttrium barium copper oxide planar resonators with two fundamental modes for circuit quantum electrodynamics experiments. We first demonstrate good tunability in the resonant microwave frequencies and in their interplay, as emerges from the dependence of the transmission spectra on the device geometry. We then investigate the magnetic coupling of the resonant modes with bulk samples of 2,2-diphenyl-1-picrylhydrazyl organic radical spins. The transmission spectroscopy performed at low temperature shows that the coherent spin-photon coupling regime with the spin ensembles can be achieved by each of the resonator modes. The analysis of the results within the framework of the input-output formalism and by means of entropic measures demonstrates coherent mixing of the degrees of freedom corresponding to two remote spin ensembles and, with a suitable choice of the geometry, the approaching of a regime with spin-induced mixing of the two photon modes
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