CNOT gate operation on a photogenerated molecular electron spin-qubit pair

Abstract

Implementation of the two-qubit controlled-NOT (CNOT) gate is necessary to develop a complete set of universal gates for quantum computing. Here, we demonstrate that a photogenerated radical (spin qubit) pair within a covalent donor-chromophore-acceptor molecule can be used to successfully execute a CNOT gate with high fidelity. The donor is tetrathiafulvalene (TTF), the chromophore is 8-aminonaphthalene-1,8-dicarboximide (ANI), and the acceptor is pyromellitimide (PI). Selective photoexcitation of ANI with a 416 nm laser pulse results in subnanosecond formation of the TTF•+-ANI-PI•− radical (spin qubit) pair at 85 K having a 1.8 µs phase memory time. This is sufficiently long to execute a CNOT gate using a sequence of five microwave pulses followed by a sequence of two pulses that read out all the elements of the density matrix. Comparing these data to a simulation of the data that assumes ideal conditions results in a fidelity of 0.97 for the execution of the CNOT gate. These results show that photogenerated molecular spin qubit pairs can be used to execute this essential quantum gate at modest temperatures, which affords the possibility that chemical synthesis can be used to develop structures to execute more complex quantum logic operations using electron spins.

Excitation Energy Transfer and Exchange‐Mediated Quartet State Formation in Porphyrin‐Trityl Systems

“…Figure S13). Some slights tructural broadening is observed in the wings of the spectrumd ue to 13 Cs atellite-transitions. [31] Compared to the spectrum of the trityl radical, the triplet state spectrumo fZ nTPP is very broad.…”

“…[3,[8][9][10] In the area of molecular spintronics, photogenerated organic multi-spins ystems have proven invaluable for exploring the fundamental requirements for spin-information transfer and storageo namolecular level. [11][12][13][14] By photoexcitation, well-defined initial spin states with strongs pin polarisation can be generated, which may then be characterisedb ya dvanced magnetic resonance techniques with regard to their magnetic properties and spin-spin interactions. Through systematic variationso ft he molecular design and ac areful study of the resultingm agnetic properties, it will ultimately be possible to establishd esign protocols for new magnetic materials exhibiting the desired properties for an efficient transfer and storage of spin information.…”

“…In the area of molecular spintronics, photogenerated organic multi‐spin systems have proven invaluable for exploring the fundamental requirements for spin‐information transfer and storage on a molecular level [11–14] . By photoexcitation, well‐defined initial spin states with strong spin polarisation can be generated, which may then be characterised by advanced magnetic resonance techniques with regard to their magnetic properties and spin‐spin interactions.…”

Electron spin resonance resolves intermediate triplet states in delayed fluorescence

“…[45][46][47] Tuning spin-orbit coupling in molecular systems and their subsequent trESR signatures, as demonstrated here, is not only of paramount importance to blue OLED development but may also find resonance more broadly in the development of organic materials for light-controlled quantum information and spintronics. [78][79][80][81][82]…”

Coherent manipulation and quantum phase interference in a fullerene-based electron triplet molecular qutrit

“…Photoexcitation has been used to generate S > 1/2 systems for a long history, with many examples showing quantum entanglement or long coherence times 19,[33][34][35][36] . Recent researches have demonstrated that a photogenerated radical pair can be utilized to perform quantum teleportation in a donor-acceptor stable radical system 37 .…”