Electrical Read-Out of a Single Spin Using an Exchange-Coupled Quantum Dot

Godfrin, C.; Thiele, Stefan; Ferhat, Abdelkarim; Klyatskaya, Svetlana; Rüben, Mario; Wernsdorfer, Wolfgang; Balestro, Franck

doi:10.1021/acsnano.7b00451

Cited by 58 publications

(40 citation statements)

References 37 publications

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“…39 Right: TbPc2, in which a quantum algorithm has been implemented for the first time at the single-molecule level. 73 The molecular approach also brings with it some intrinsic limitations for the achievement of very long spin-coherence times. The main sources of decoherence in molecular materials involve interactions with (i) thermal vibrations of the molecule and/or the extended lattice (phonons), (ii) nuclear spins (coming for example from hydrogen or nitrogen atoms) located on the ligands and solvent, and (iii) neighbouring electronic spins.…”

Section: Molecular Spin Qubitsmentioning

confidence: 99%

“…40 Recently, the same set-up has enabled read-out of the electronic spin state of the same molecule. 73 The extension of this idea to different magnetic molecules has also been proposed. 74 Although very promising, this approach still lacks a mechanism for coherently 'wiring up' the individual molecular qubits with each other.…”

Section: From the Single Crystal To The Single Moleculementioning

confidence: 99%

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Molecular spins for quantum computation

et al. 2019

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Spins in solids or in molecules possess discrete energy levels, and the associated quantum states can be tuned and coherently manipulated by means of external electromagnetic fields. Spins therefore provide one of the simplest platforms to encode a quantum bit (qubit), the elementary unit of future quantum computers. Performing any useful computation demands much more than realizing a robust qubit-one also needs a large number of qubits and a reliable manner with which to integrate them into a complex circuitry that can store and process information and implement quantum algorithms. This 'scalability' is arguably one of the challenges for which a chemistry-based bottom-up approach is best-suited. Molecules, being much more versatile than atoms and yet microscopic, are the quantum objects with the highest capacity to form non-trivial ordered states at the nanoscale and to be replicated in large numbers using chemical tools. This Perspective discusses how chemistry can contribute to the design of robust spin systems based on mononuclear rare-earth complexes. Using these molecular nanomagnets as key examples, we illustrate the variety of paths that chemistry has recently opened for quantum technologies: from the design of molecular spin qubits with enhanced quantum coherence to the coupling of these for implementing quantum logic gates and, finally, to the integration of such molecular quantum units into devices.

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Section: Molecular Spin Qubitsmentioning

confidence: 99%

Section: From the Single Crystal To The Single Moleculementioning

confidence: 99%

Molecular spins for quantum computation

et al. 2019

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“…Due to the exchange coupled properties, the spin dot can influence the transport properties of the read-out dot, leading to the observation of the fingerprint magnetic properties of the Tb 3+ ion in the current passing through a single TbPc 2 molecule. 86 Differential conductance studies (dI/dV) as a function of drain-source voltage (V ds ) and gate voltage (V g ) revealed a single charge-degeneracy point with a weak spin S = ½ Kondo effect, which is ascribed to the π-radical delocalised over the Pc rings. Since the S = ½ is ferromagnetically coupled to the magnetic moment carried by the Tb 3+ ion by ferromagnetic interaction, which is hyperfine coupled to the nuclear spin states, the transport properties through the aromatic Pc ligands (read-out dot) reflect the whole spin cascade | = 1/2⟩|| = 6⟩|| = 3/ 2 ⟩.…”

Section: Readoutmentioning

confidence: 99%

Molecular spin qudits for quantum algorithms

et al. 2018

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Presently, one of the most ambitious technological goals is the development of devices working under the laws of quantum mechanics. One prominent target is the quantum computer, which would allow the processing of information at quantum level for purposes not achievable with even the most powerful computer resources. The large-scale implementation of quantum information would be a game changer for current technology, because it would allow unprecedented parallelised computation and secure encryption based on the principles of quantum superposition and entanglement. Currently, there are several physical platforms racing to achieve the level of performance required for the quantum hardware to step into the realm of practical quantum information applications. Several materials have been proposed to fulfil this task, ranging from quantum dots, Bose-Einstein condensates, spin impurities, superconducting circuits, molecules, amongst others. Magnetic molecules are among the list of promising building blocks, due to (i) their intrinsic monodispersity, (ii) discrete energy levels (iii) the possibility of chemical quantum state engineering, and (iv) their multilevel characteristics that lead to Qudits, where the dimension of the Hilbert space is d > 2. Herein we review how a molecular nuclear spin qudit, (d = 4), known as TbPc, gathers all the necessary requirements to perform as a molecular hardware platform with a first generation of molecular devices enabling even quantum algorithm operations.

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“…The coloured rectangles in Figure 1(b) indicate the position of the avoided level crossings where Quantum Tunnelling of the Magnetization (QTM) can occur. We previously reported that the magnetic moment both of the single electronic and nuclear spin can be read-out via transport measurements [11,31] and that coherent manipulation of a single nuclear spin can be performed using electric fields only [32]. In solid state devices, the read-out and coherent manipulation of a nuclear spin was also achieved for Nitrogen-Vacancy centers in diamond [9] and ionized 31 P donor in Silicon [10].…”

Section: Reading-out Nuclear Spin Statesmentioning

confidence: 99%

Operating Quantum States in Single Magnetic Molecules: Implementation of Grover’s Quantum Algorithm

et al. 2017

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Quantum algorithms use the principles of quantum mechanics, such as, for example, quantum superposition, in order to solve particular problems outperforming standard computation. They are developed for cryptography, searching, optimization, simulation, and solving large systems of linear equations. Here, we implement Grover's quantum algorithm, proposed to find an element in an unsorted list, using a single nuclear 3/2 spin carried by a Tb ion sitting in a single molecular magnet transistor. The coherent manipulation of this multilevel quantum system (qudit) is achieved by means of electric fields only. Grover's search algorithm is implemented by constructing a quantum database via a multilevel Hadamard gate. The Grover sequence then allows us to select each state. The presented method is of universal character and can be implemented in any multilevel quantum system with nonequal spaced energy levels, opening the way to novel quantum search algorithms.

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Electrical Read-Out of a Single Spin Using an Exchange-Coupled Quantum Dot

Cited by 58 publications

References 37 publications

Molecular spins for quantum computation

Molecular spins for quantum computation

Molecular spin qudits for quantum algorithms

Operating Quantum States in Single Magnetic Molecules: Implementation of Grover’s Quantum Algorithm

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