Tuning of molecular qubits: very long coherence and spin–lattice relaxation times

Bader, Katharina; Winkler, Mario; Slageren, Joris van

doi:10.1039/c6cc00300a

Cited by 115 publications

(114 citation statements)

References 36 publications

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“…Additionally, a lower spin density could extend coherence times by improving magnetic isolation of dopant ions. For example, spin coherence times ranging from microseconds up to ∼1 ms have been observed in other, more well-isolated transition metal ion systems [27,29,54,55].…”

Section: Discussionmentioning

confidence: 99%

Resonant optical spectroscopy and coherent control ofCr4+spin ensembles in SiC and GaN

et al. 2017

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Spins bound to point defects are increasingly viewed as an important resource for solid-state implementations of quantum information and spintronic technologies. In particular, there is a growing interest in the identification of new classes of defect spin that can be controlled optically. Here, we demonstrate ensemble optical spin polarization and optically detected magnetic resonance (ODMR) of the S = 1 electronic ground state of chromium (Cr 4+ ) impurities in silicon carbide (SiC) and gallium nitride (GaN). Spin polarization is made possible by the narrow optical linewidths of these ensembles (<8.5 GHz), which are similar in magnitude to the ground state zero-field spin splitting energies of the ions at liquid helium temperatures. This allows us to optically resolve individual spin sublevels within the ensembles at low magnetic fields using resonant excitation from a cavity-stabilized, narrow-linewidth laser. Additionally, these near-infrared emitters possess exceptionally weak phonon sidebands, ensuring that >73% of the overall optical emission is contained with the defects' zero-phonon lines. These characteristics make this semiconductor-based, transition metal impurity system a promising target for further study in the ongoing effort to integrate optically active quantum states within common optoelectronic materials.

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Section: Discussionmentioning

confidence: 99%

Resonant optical spectroscopy and coherent control ofCr4+spin ensembles in SiC and GaN

et al. 2017

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“…The ligand effect on the quantum coherence times was also investigated using complexes CuPc Cl 12 and CuPc F 13. All the three complexes share a similar T 2 value of 40 µs at 7 K, indicating the ligand field effect is little in this series [31]. Except for V(IV), Cu(II) is another ion with spin-1/2 state.…”

Section: Cu(ii) Based Single-ion Spin Qubitsmentioning

confidence: 82%

“…Together with its d 1 electron configuration, this molecule makes a perfect two level system for spin qubit. Moreover, the out-of-phase signals of AC magnetic susceptibility for the frequency of 10 kHz can be observed up to 40 K under an applied static magnetic field of 0.2 T. An extraordinarily long T1 (2.4 s at 7 K) was obtained by Q-band EPR measurements in 0.5 mM D2SO4-solution, and T2 is 20 μs at 20 K under the same condition [31]. When VOPc is mixed with the isostructural diamagnetic host TiOPc in molar ratio of 1:1000, quantum coherence could be detected up to room temperature.…”

Section: Introductionmentioning

confidence: 94%

“…With the Hahn echo sequence, T 2 for 11 was determined to be 1 µs at 80 K. Moreover, Rabi oscillations of a 0.1% CuPc:H 2 Pc were clearly observed at 5 K (Figure 6c) [49]. The impact of solvent deuteration on electron spin relaxation has been investigated by dissolving 11 in H 2 SO 4 and D 2 SO 4 [31]. For D 2 SO 4 , T 2 is about 41 µs at 7 K, which is five times longer than those in H 2 SO 4 ( Figure 6b).…”

Section: Cu(ii) Based Single-ion Spin Qubitsmentioning

confidence: 99%

“…Moreover, a pronounced crystal size dependence of the relaxation time was observed in complexes 6-8. Another mononuclear V(IV) based spin qubits with short V=O bond (1.58 Å) is the complex VOPc 9 (Pc = Phthalocyanine) (Figure 4a) [31,48]. Together with its d 1 electron configuration, this molecule makes a perfect two level system for spin qubit.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Rise of Single-Ion Magnets as Spin Qubits

2016

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Recent studies revealed that magnetic molecules with single spin centers showed exciting phenomena related to quantum information processing, such as long quantum coherence times and Rabi oscillations. In this review, we go over these phenomena according to the essential metal ions, from which we can see the development of single-ion magnets as spin qubits is booming, especially quantum coherence times have been significantly enhanced from nanoseconds to hundreds of microseconds in a short period. Hence, the correlations between the molecular structures and quantum coherence are becoming clearer. In this regard, some chemical approaches to designing better spin qubits have been discussed.

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A Porphyrin Spin Qubit and Its 2D Framework Nanosheets

Urtizberea

Natividad

Alonso

et al. 2018

Adv Funct Materials

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Molecular spin qubits have been shown to reach sufficiently long quantum coherence times to envision their use as hardware in quantum processors. These will however require their implementation in hybrid solid-state devices for which the controlled localization and homogeneous orientation of the molecular qubits will be necessary. An alternative to isolated molecules that can ensure these key aspects is 2D framework in which the qubit would act as node. In this work, it is demonstrated that the isolated metalloporphyrin [Cu(H 4 TCPP)] molecule is a potential spin qubit, and maintains similar quantum coherence as node in a 2D [{CuTCPP}Zn 2 (H 2 O) 2 ] metal-organic framework. Mono-and multilayer deposits of nanosheets of a similar 2D framework are then successfully formed following a modular method based on Langmuir-Schaefer conditions. The orientation of the {CuTCPP} qubit nodes in these nanosheets is homogeneous parallel to the substrate. These nanosheets are also formed with a control over the qubit concentration, i.e., by dilution with the unmetallated porphyrin. Eventually, 2D nanosheets are formed in situ directly on a substrate, through a simple protocol devised to reproduce the Langmuir-Schaefer conditions locally. Altogether these studies show that 2D spin qubit frameworks are ideal components to develop a hybrid quantum computing architecture. and gates first arose in the form of purely organic systems, using either the multiple nuclear spins of rationally selected molecules or the electronic spin(s) of open shell organic molecules bearing one or multiple radicals. The careful design and selection of such organic molecules coupled to sophisticated experiments have allowed implementing realistic quantum operations using ensembles of these. [2] Paramagnetic coordination complexes were later proposed as alternative molecular spin qubits, after it was argued and shown that the molecule electronic spin orientation and quantum superpositions allow to encode quantum bit (qubit) states. [3] Recent improvements in the coherence times of these molecular spin qubits [4] and the unique ability to design molecules with multiple qubits as prototypes of quantum gates [5] have brought this scheme to a point where it becomes reasonable to envision the design of a magnetic quantum processor. A magnetic molecule has even recently been used to implement Grover's quantum algorithm, albeit using its metal ion nuclear spin. [6] One of the advantages of the molecular scheme is that macroscopic numbers of identical qubits are obtained in one sole reaction. While this is appealing for the daunting challenge of scaling to a usable size, common to all proposed schemes, [7] the technology to build a scalable quantum architecture based on molecular qubits is

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Tuning of molecular qubits: very long coherence and spin–lattice relaxation times

Cited by 115 publications

References 36 publications

Resonant optical spectroscopy and coherent control ofCr4+spin ensembles in SiC and GaN

Resonant optical spectroscopy and coherent control ofCr4+spin ensembles in SiC and GaN

The Rise of Single-Ion Magnets as Spin Qubits

A Porphyrin Spin Qubit and Its 2D Framework Nanosheets

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