Measurement of quantum coherence in thin films of molecular quantum bits without post-processing

Lenz, Samuel; Kern, Bastian; Schneider, Martin; Slageren, Joris van

doi:10.1039/c9cc02184a

Cited by 13 publications

(11 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First we investigated the steady‐state response of the hybrid quantum system consisting of a 9.4 mg (≈6 × 10 18 spins) pressed powder sample of the stable free radical α,γ‐bisdiphenylene‐β‐phenylallyl benzene solvate (, abbreviated BDPA hereafter) mounted on the bottom, flat mirror of a semi‐confocal copper Fabry–Pérot resonator (FPR). [ 47 ] To this end, we recorded the radiation reflected from the cavity ( S 11 scattering parameter) as a function of external magnetic field B 0 and microwave frequency by means of a vector network analyzer at a temperature of T = 7 K ( Figure A). The first resonance mode (i.e., that with smallest inter‐mirror separation) of the cavity was tuned to 35.000 GHz prior to the measurement.…”

Section: Resultsmentioning

confidence: 99%

“…The data were corrected for diamagnetic contributions using Pascal's constants. All strong coupling experiments were carried out employing a home‐built Fabry–Pérot resonator (FPR) made of copper, [ 47 ] inserted into an Oxford Instruments CF935 continuous flow helium cryostat. Samples were pressed into 5 mm pellets.…”

Section: Methodsmentioning

confidence: 99%

“…Here, we present investigations of ensembles of stable organic radicals (benzene complex of α,γ‐bisdiphenylene‐β‐phenylallyl (≡ BDPA·Bz), Figure S1, Supporting Information), by means of a specially designed 3D resonator of the Fabry–Pérot type that has highly enhanced microwave field homogeneity compared to conventional electron paramagnetic resonance (EPR) resonators. [ 47 ] We achieve the strong coupling regime up to room temperature. We investigate the spin dynamics by pulsed microwave measurements with both weak and strong pulses.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Room‐Temperature Quantum Memories Based on Molecular Electron Spin Ensembles

et al. 2021

Self Cite

View full text Add to dashboard Cite

Superconducting quantum bits are addressed by means of microwave radiation and quantum memories in this context thus need to be able to store microwave photon states. To this end, resonant structures for electromagnetic radiation can be used to strongly couple quantum bits and quantum memories to quantized cavity modes of the electromagnetic field. The strong coupling generates a hybrid quantum system that allows mapping the qubit state onto the cavity field state. [6] This strategy has given rise to the field of cavity quantum electrodynamics and has already been used to couple two superconducting qubits together via a cavity bus. [7] A second application of quantum memories is in quantum repeaters for quantum communication. Because telecom wavelengths are in the near-infrared, for this application, optical quantum memories are required that store optical photon states. [8] Considering the choice of material platform for designing microwave quantum memories, electron spins in solids can be easily addressed by microwave pulses and have been shown to possess excellent coherence times up to seconds, for some systems even up to room temperature. [9][10] Unfortunately, the coupling of a single electron spin to a photon is very weak. Although resonant structures can be tailored to improve single-spin coupling, [11][12][13] the weakness of the coupling renders addressing individual spins by means of coupling to cavity modes very challenging. This can be overcome by using an electron spin ensemble rather than single spins, because the coupling strength of a spin ensemble to an electromagnetic resonator mode is proportional to the square root of the number of electron spins in the ensemble. [14] This then leads to the general idea of the implementation of a microwave quantum memory using spin ensembles and microwave resonators (Figure 1). The state to be stored is encoded in a weak microwave pulse and sent to the hybrid quantum system constituted of an electron spin ensemble that is strongly coupled to a microwave resonator, where it is stored. When the quantum state is needed again, a strong microwave pulse is sent to the resonator, which leads to deterministic retrieval of the quantum state that is emitted as a microwave photon to be used as desired.Strong coupling between cavity and electron spin ensembles has been observed in a variety of spin systems, including organic radicals, [15][16][17][18][19][20] phosphorous dopants in silicon, [21,22] P1 and nitrogen vacancy (NV) defects in diamond, [23][24][25][26][27][28][29][30][31][32] N@ C 60 , [33] rare earth dopants in oxides, [34,35] transition metal Whilst quantum computing has recently taken great leaps ahead, the development of quantum memories has decidedly lagged behind. Quantum memories are essential devices in the quantum technology palette and are needed for intermediate storage of quantum bit states and as quantum repeaters in long-distance quantum communication. Current quantum memories operate at cryogenic, mostly sub-Kelvin temperatures and require extens...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Room‐Temperature Quantum Memories Based on Molecular Electron Spin Ensembles

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…For these measurements, we have used our recently developed Q‐band Fabry–Pérot resonator that is optimized for flat samples such as the present thin films. [ 58 ] Figure a shows the ESE spectrum recorded at 7 K on a 6P/0.9[Cu]/– thin film deposited by spin‐coating. The low‐field part of the spectrum (1.07–1.23 T) is typical for a species with an axial g ‐tensor and is attributed to [Cu(dbm) 2 ], confirming the intactness of the MQBs in the polymer film.…”

Section: Resultsmentioning

confidence: 99%

“…Pulsed EPR measurements were carried out using a home-built pulsed Q-Band (35.000 GHz) spectrometer, equipped with an Oxford Instruments CF935O helium flow cryostat, and a home-built brass Fabry-Pérot resonator. [58,64] For the field-swept echo-detected spectra, the Hahn echo sequence was used with pulse lengths of 40 and 80 ns, as well as an interpulse delay of 300 ns. Easyspin was used for spectrum simulation.…”

Section: Semiconductor Film Preparationmentioning

confidence: 99%

Hybrid Spintronic Materials from Conducting Polymers with Molecular Quantum Bits

Kern

Tesi

Neußer

et al. 2020

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

Hybrid materials consisting of organic semiconductors and molecular quantum bits promise to provide a novel platform for quantum spintronic applications. However, investigations of such materials, elucidating both the electrical and quantum dynamical properties of the same material have never been reported. Here the preparation of hybrid materials consisting of conducting polymers and molecular quantum bits is reported. Organic field-effect transistor measurements demonstrate that the favorable electrical properties are preserved in the presence of the qubits. Chemical doping introduces charge carriers into the material, and variable-temperature charge transport measurements reveal the existence of mobile charge carriers at temperatures as low as 15 K. Importantly, quantum coherence of the qubit is shown to be preserved up to temperatures of at least 30 K, that is, in the presence of mobile charge carriers. These results pave the way for employing such hybrid materials in novel molecular quantum spintronic architectures.

show abstract

Modular Approach to Creating Functionalized Surface Arrays of Molecular Qubits

et al. 2023

Self Cite

View full text Add to dashboard Cite

The quest for developing quantum technologies is driven by the promise of exponentially faster computations, ultrahigh performance sensing, and achieving thorough understanding of many‐particle quantum systems. Molecular spins are excellent qubit candidates because they feature long coherence times, are widely tunable through chemical synthesis, and can be interfaced with other quantum platforms such as superconducting qubits. A present challenge for molecular spin qubits is their integration in quantum devices, which requires arranging them in thin films or monolayers on surfaces. However, clear proof of the survival of quantum properties of molecular qubits on surfaces has not been reported so far. Furthermore, little is known about the change in spin dynamics of molecular qubits going from the bulk to monolayers. Here, a versatile bottom‐up method is reported to arrange molecular qubits as functional groups of self‐assembled monolayers (SAMs) on surfaces, combining molecular self‐organization and click chemistry. Coherence times of up to 13 µs demonstrate that qubit properties are maintained or even enhanced in the monolayer.

show abstract

Measurement of quantum coherence in thin films of molecular quantum bits without post-processing

Abstract: A novel Fabry–Pérot pulsed EPR resonator with very good microwave magnetic field homogeneity allows facile measurement of thin films of molecular quantum bits.

Cited by 13 publications

References 24 publications

Room‐Temperature Quantum Memories Based on Molecular Electron Spin Ensembles

Room‐Temperature Quantum Memories Based on Molecular Electron Spin Ensembles

Hybrid Spintronic Materials from Conducting Polymers with Molecular Quantum Bits

Modular Approach to Creating Functionalized Surface Arrays of Molecular Qubits

Contact Info

Product

Resources

About