Periodic Reporting for period 1 - CASTLE (Chirality and spin selectivity in electron transfer processes: from quantum detection to quantum enabled technologies)
Berichtszeitraum: 2023-01-01 bis 2024-06-30
Molecular spins are promising building blocks of future quantum technologies thanks to the unparalleled flexibility provided by chemistry, which allows the design of complex structures targeted for specific applications. However, their weak interaction with external stimuli makes it difficult to access their state at
the single-molecule level, a fundamental tool for their use, for example, in quantum computing and sensing. Here, an innovative solution exploiting the interplay between chirality and magnetism using the chirality-induced spin selectivity effect on electron transfer processes is foreseen. It is envisioned to use a spin-to-charge conversion mechanism that can be realized by connecting a molecular spin qubit to a dyad where an electron donor and an electron acceptor are linked by a chiral bridge.
The long-term vision of the present proposal is to transform the Chirality Induced Spin Selectivity effect into an enabling technology for quantum applications. This overarching and ambitious goal will be pursued by achieving four key objectives:
O1: Establish the CISS effect at the intramolecular level
O2: Investigate the quantum properties of the CISS effect through coherent detection methods
O3: Model the CISS effect at the quantum mechanical level and design quantum applications
O4: Demonstrate CISS-based initialization and readout in a quantum device
To achieve these goals CASTLE will leverage the complementary background, competencies, and capabilities of the teams of four PIs who are international leaders in their respective fields.
• UNIFI brings in the project the expertise in the design of magnetic molecular systems and the demonstrated ability to develop novel concepts in magnetism exploiting the quantum nature of molecules even at the nanoscale.
• NWU brings integrative experience in preparing and characterizing molecular qubits generated using photo-induced ET and probed using cutting-edge transient laser and EPR spectroscopies.
• FUB contributes to developing innovative tools for the investigation and the exploitation of the CISS effect in quantum materials with expertise and state-of-the-art facilities for pulsed and time-resolved magnetic resonance techniques, including electrically detected magnetic resonance (EDMR) pioneered by PI3.
• UNIPR brings in the project a unique combination of competencies in developing realistic models and quantum computing schemes for molecular spin systems and in unconventional nuclear magnetic resonance techniques, offering facilities that fully complement those at FUB and NWU.
• The team will also include as a partner the Weizmann Institute with the pioneer of CISS Prof. Ron Naaman. Beyond a relevant advisory role, WI will contribute with application-oriented facilities for the production of CISS-based molecular devices as proof-of-principle of qubit control and readout.
A second partner organization is the Italian National Interuniversity Consortium of Material Science and Technology (INSTM) bringing in the complementary synthetic expertise in organic and metal/organic chemistry.
Visit https://www.castle.unifi.it/(öffnet in neuem Fenster) for more information.
the single-molecule level, a fundamental tool for their use, for example, in quantum computing and sensing. Here, an innovative solution exploiting the interplay between chirality and magnetism using the chirality-induced spin selectivity effect on electron transfer processes is foreseen. It is envisioned to use a spin-to-charge conversion mechanism that can be realized by connecting a molecular spin qubit to a dyad where an electron donor and an electron acceptor are linked by a chiral bridge.
The long-term vision of the present proposal is to transform the Chirality Induced Spin Selectivity effect into an enabling technology for quantum applications. This overarching and ambitious goal will be pursued by achieving four key objectives:
O1: Establish the CISS effect at the intramolecular level
O2: Investigate the quantum properties of the CISS effect through coherent detection methods
O3: Model the CISS effect at the quantum mechanical level and design quantum applications
O4: Demonstrate CISS-based initialization and readout in a quantum device
To achieve these goals CASTLE will leverage the complementary background, competencies, and capabilities of the teams of four PIs who are international leaders in their respective fields.
• UNIFI brings in the project the expertise in the design of magnetic molecular systems and the demonstrated ability to develop novel concepts in magnetism exploiting the quantum nature of molecules even at the nanoscale.
• NWU brings integrative experience in preparing and characterizing molecular qubits generated using photo-induced ET and probed using cutting-edge transient laser and EPR spectroscopies.
• FUB contributes to developing innovative tools for the investigation and the exploitation of the CISS effect in quantum materials with expertise and state-of-the-art facilities for pulsed and time-resolved magnetic resonance techniques, including electrically detected magnetic resonance (EDMR) pioneered by PI3.
• UNIPR brings in the project a unique combination of competencies in developing realistic models and quantum computing schemes for molecular spin systems and in unconventional nuclear magnetic resonance techniques, offering facilities that fully complement those at FUB and NWU.
• The team will also include as a partner the Weizmann Institute with the pioneer of CISS Prof. Ron Naaman. Beyond a relevant advisory role, WI will contribute with application-oriented facilities for the production of CISS-based molecular devices as proof-of-principle of qubit control and readout.
A second partner organization is the Italian National Interuniversity Consortium of Material Science and Technology (INSTM) bringing in the complementary synthetic expertise in organic and metal/organic chemistry.
Visit https://www.castle.unifi.it/(öffnet in neuem Fenster) for more information.
• The first step in the implementation of the CASTLe project has been the definition of a roadmap for transforming the CISS effect into an enabling technology for quantum information science (Adv. Mater., 2023, 35, 2300472). . In particular, we performed numerical simulations of initialization, one- and two-qubit gates and readout of a molecular spin linked to a D--A unit. Here the CISS effect is exploited to control individual molecular spins, potentially overcoming important limitations of current technology
• Key to the realization of a CISS-based spin control is the demonstration that the phenomenon occurs at the molecular in electron transfer processes. This was done by studying with time-resolved Electron Paramagnetic Resonance (trEPR) chiral D--A molecules and corresponding achiral reference systems, aligned with liquid crystals with the CISS axis either parallel or perpendicular to the external field. The experiments showed a clear feature in the spectrum of chiral molecules, absent in the achiral reference, which were interpreted as unambiguous evidence of the CISS effect. (Science, 2023, 382, 197-201).
• We explored through transport experiments the CISS efficiency of thia-bridged hetero-helicenes that can also act as electron donor, and we detected high efficiency and low-voltage conductivity in both neutral (ACS Nano, 2023, 17, 15189) and radical cationic (J. Mater. Chem. C, 2024, 12, 10029) forms. The same hetero-helicene has been coupled with an electron acceptor, and photoinduced electron transfer has been investigated. The first long-lived radical pair comprising a helicene has been found.
• We developed a description of the electron-transfer dynamics by Haberkorn effective formalism in the presence of CISS and consequent polarization of the transferred electron. This approach was used to simulate CISS-enabled initialization, readout and implementation of quantum gates.
• We developed the first model explicitly including the bridge degrees of freedom to model electron transfer in donor-chiral bridge-acceptor molecules. The model was solved numerically on short chiral chains, demonstrating that a sizable polarization on the acceptor arises from the interplay of coherent and incoherent dynamics, with a crucial role of strong electron-electron correlations (https://doi.org/10.48550/arXiv.2406.15135(öffnet in neuem Fenster)).
• The team has also investigated molecular spin qubits and quantum gates based on vanadium(IV) and copper(II) as potential candidates to be integrated into the chiral A/D dyads.
Porphyrin-based Vanadium(IV) and Copper(II) spin qubits have been investigated from the perspective of using these building blocks coupled to photo-generated spins. The first experiments using a free-base porphyrin as the chromophore evidenced high electronic and nuclear spin polarization of the vanadium spin qubit coupled to the photoexcited S=1 of the nearby porphyrin.
• Two Muon Spin Rotation (MuSR) experiments were approved at the ISIS facility. A preliminary run was performed to sort the better solvents for frozen glasses. The crucial pump-probe experiment is scheduled at a later stage to allow for the development of a very challenging sample cell.
• A setup for an optically pumped NMR instrument to investigate CISS is being developed. It exploits the newly acquired high repetition rate 3rd harmonic Nd-YAG pumped OPO laser.
• Key to the realization of a CISS-based spin control is the demonstration that the phenomenon occurs at the molecular in electron transfer processes. This was done by studying with time-resolved Electron Paramagnetic Resonance (trEPR) chiral D--A molecules and corresponding achiral reference systems, aligned with liquid crystals with the CISS axis either parallel or perpendicular to the external field. The experiments showed a clear feature in the spectrum of chiral molecules, absent in the achiral reference, which were interpreted as unambiguous evidence of the CISS effect. (Science, 2023, 382, 197-201).
• We explored through transport experiments the CISS efficiency of thia-bridged hetero-helicenes that can also act as electron donor, and we detected high efficiency and low-voltage conductivity in both neutral (ACS Nano, 2023, 17, 15189) and radical cationic (J. Mater. Chem. C, 2024, 12, 10029) forms. The same hetero-helicene has been coupled with an electron acceptor, and photoinduced electron transfer has been investigated. The first long-lived radical pair comprising a helicene has been found.
• We developed a description of the electron-transfer dynamics by Haberkorn effective formalism in the presence of CISS and consequent polarization of the transferred electron. This approach was used to simulate CISS-enabled initialization, readout and implementation of quantum gates.
• We developed the first model explicitly including the bridge degrees of freedom to model electron transfer in donor-chiral bridge-acceptor molecules. The model was solved numerically on short chiral chains, demonstrating that a sizable polarization on the acceptor arises from the interplay of coherent and incoherent dynamics, with a crucial role of strong electron-electron correlations (https://doi.org/10.48550/arXiv.2406.15135(öffnet in neuem Fenster)).
• The team has also investigated molecular spin qubits and quantum gates based on vanadium(IV) and copper(II) as potential candidates to be integrated into the chiral A/D dyads.
Porphyrin-based Vanadium(IV) and Copper(II) spin qubits have been investigated from the perspective of using these building blocks coupled to photo-generated spins. The first experiments using a free-base porphyrin as the chromophore evidenced high electronic and nuclear spin polarization of the vanadium spin qubit coupled to the photoexcited S=1 of the nearby porphyrin.
• Two Muon Spin Rotation (MuSR) experiments were approved at the ISIS facility. A preliminary run was performed to sort the better solvents for frozen glasses. The crucial pump-probe experiment is scheduled at a later stage to allow for the development of a very challenging sample cell.
• A setup for an optically pumped NMR instrument to investigate CISS is being developed. It exploits the newly acquired high repetition rate 3rd harmonic Nd-YAG pumped OPO laser.
The most relevant result of the first year of the project is the demonstration that chirality-induced spin selectivity is active in electron transfer at the molecular level. This ground breaking result pushes the entire field beyond the state of the art. From the fundamental point of view, it adds a new degree of freedom in the electron transfer reactions. The impact is not limited to the field of quantum technologies, i.e. for molecular spin qubits initialization, control, and readout. As commented on Science by Joseph E. Subotnik "These results suggest that the standard ET theory should be modified to include both energy and total (orbital plus spin) angular momentum conservation, thereby opening the door to new CISS applications, including “green” hydrogen generation. " The use of the CISS effect to polarize not only the electron spin but also the nuclear ones will be also explored in the next phases of the CASTLe project.