The N@C₆₀ nuclear spin qubit: Bang‐bang decoupling and ultrafast phase gates

Abstract

Nuclear spins have been proposed for the embodiment of quantum information and yielded the most complex demonstrations of quantum algorithms to date. However, the weak thermal polarisation of nuclear spins in experimentally accessible conditions has presented a barrier to further scaling. Here, we discuss the benefits of a coupled electron spin to the nuclear spin qubit and demonstrate the ideas using the 14 N nuclear spin in the N@C 60 molecule. In addition to providing a resource for nuclear spin polarisation and detection, the electron spin can be exploited to perform ultrafast nuclear spin phase gates, which can in turn be used to dynamically bang-bang decouple the nuclear spin from unwanted interactions.

Intrinsic origin of spin echoes in dipolar solids generated by strongπpulses

“…8,9,10,11,12 In real experiments, all pulses are finite in amplitude and have nonzero duration. Nevertheless, for pulse sequences with a large number of π/2 pulses, 13,14 such as in NMR line-narrowing sequences, 3,5,15,16,17,18,19 using the delta-function pulse approximation yields qualitatively correct predictions.…”

“…7,8,9,10,11,12 Typically, the deltafunction pulse approximation is used in the analysis. While we have not considered all possible internal Hamiltonians, or pulse types, we caution the reader that the validity of the delta-function pulse approximation should be checked for each system.…”

Electronic Structures, and Optical and Magnetic Properties of Quadruple-Decker Phthalocyanines

“…For instance, single-molecule magnets using copper phthalocyanine [1], nitrogen, and phosphorous atom in fullerene cages, such as N@C 60 [2], and P@C 60 , endohedral metallofullerene, such as Sc 3 N@C 80 [3], Sc 3-x YN@C 80 (CF 3 ) n [4,5], Gd x Sc 3-x N@C 80 [6], HoSc 2 N@C 80 [7], LnSc 2 N@C 80 [8], (Sc 3 N@C 80 ) 2 dimmer [9], scandium oxide endohedral metallofullerenes Sc 4 O 2 @C 80 (CF 3 ) n , Sc 4 O 2 @C 80 [10,11], and endohedral metallofullerene encapsulated within single-walled-carbon nanotube (SWCNTs) as peapods [12][13][14], were applied for controlling the magnetic interaction with entanglement of quantum spin in the spinlattice relaxation process. Experimental verification of spintronics, and nuclear magnetic resonance (NMR) quantum computers using single nitrogen vacancy defects in the center of diamonds [15], perfluorobutadienyl iron complex [16], nitrogen endohedral fullerenes, vanadium phthalocyanines [17], and single-molecule magnets [18,19] were performed for analyzing spin dynamics, Rabi oscillation, and entanglement of nuclear spin as quantum bits in quantum algorithm calculation.…”

Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

“…Development of some quantum computers using nitrogen vacancy diamond and metal complexes has been reported [1,2]. In improving performance of nuclear magnetic resonance (NMR) quantum computer, molecular design of metal complex with spin multiplicity, spin superposition in molecule, parallel calculation in relaxation time are important factors.…”