6 research outputs found
Coherent storage of photoexcited triplet states using 29Si nuclear spins in silicon
Pulsed electron paramagnetic resonance spectroscopy of the photoexcited,
metastable triplet state of the oxygen-vacancy center in silicon reveals that
the lifetime of the ms = \pm1 sub-levels differ significantly from that of the
ms =0 state. We exploit this significant difference in decay rates to the
ground singlet state to achieve nearly ~100% electron spin polarization within
the triplet. We further demonstrate the transfer of a coherent state of the
triplet electron spin to, and from, a hyperfine-coupled, nearest-neighbor 29Si
nuclear spin. We measure the coherence time of the 29 Si nuclear spin employed
in this operation and find it to be unaffected by the presence of the triplet
electron spin and equal to the bulk value measured by nuclear magnetic
resonance.Comment: 5 pages, 4 figure
Ultrafast entangling gates between nuclear spins using photo-excited triplet states
The representation of information within the spins of electrons and nuclei
has been powerful in the ongoing development of quantum computers. Although
nuclear spins are advantageous as quantum bits (qubits) due to their long
coherence lifetimes (exceeding seconds), they exhibit very slow spin
interactions and have weak polarisation. A coupled electron spin can be used to
polarise the nuclear spin and create fast single-qubit gates, however, the
permanent presence of electron spins is a source of nuclear decoherence. Here
we show how a transient electron spin, arising from the optically excited
triplet state of C60, can be used to hyperpolarise, manipulate and measure two
nearby nuclear spins. Implementing a scheme which uses the spinor nature of the
electron, we performed an entangling gate in hundreds of nanoseconds: five
orders of magnitude faster than the liquid-state J coupling. This approach can
be widely applied to systems comprising an electron spin coupled to multiple
nuclear spins, such as NV centres, while the successful use of a transient
electron spin motivates the design of new molecules able to exploit
photo-excited triplet states.Comment: 5 pages, 3 figure
Entangling nuclear spins using photoexcited triplet states
Entanglement is one of the most technologically important quantum phenomena and its con- trolled creation brings us a step closer to the realisation of a quantu~ computer. Hybrid electron and nuclear spin systems which combine long nuclear de coherence times with the high polarisation and rapid processing times of electron spins are considered reliable candidates for the represen- tation of the fundamental building block of a quantum computer, the qubit. In the literature electron spins quite ofter play the role of a mediator which can access, manipulate and couple states with long coherence times, beneficial for storing quantum information. Despite the fact that an electron spin can be a useful resource for nuclear spin systems, its permanent presence can be a source of decoherence. The use of transient photo excited electron spins provide an additional advantage and once the operations which involve the electron spin are completed, the electron spin can decay and not interfere further with the evolution of the system. In this thesis we report magnetic resonance experiments and density functional theory calcu- lations for the demonstration of nuclear - nuclear entanglement using photo excited triplet states. We study homonuclear and heteronuclear fullerene derivatives and we identify in each case the relevant parameters that can lead to high fidelity entangling operations. The hyperfine interac- tion in a homonuclear system is the key parameter which determines the degree of entanglement between the nucelar spins according to a recent theoretical proposal. We measure and calculate the hyperfine interaction in homo nuclear systems with 13C nuclear spins in order to prove the feasibility of this scheme. Further experiments on a fullerene system with two nuclear spins a 31 P and a 1 H show that entangling operations of high fidelity which involve the demonstration of CNOT gates, are possible within the lifetime of the triplet state.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Entangling nuclear spins using photoexcited triplet states
Entanglement is one of the most technologically important quantum phenomena and its con-trolled creation brings us a step closer to the realisation of a quantum computer. Hybrid electron and nuclear spin systems which combine long nuclear decoherence times with the high polarisation and rapid processing times of electron spins are considered reliable candidates for the representation of the fundamental building block of a quantum computer, the qubit. In the literature electron spins quite often play the role of a mediator which can access, manipulate and couple states with long coherence times, beneficial for storing quantum information. Despite the fact that an electron spin can be a useful resource for nuclear spin systems, its permanent presence can be a source of decoherence. The use of transient photoexcited electron spins provide an additional advantage and once the operations which involve the electron spin are completed, the electron spin can decay and not interfere further with the evolution of the system. In this thesis we report magnetic resonance experiments and density functional theory calculations for the demonstration of nuclear - nuclear entanglement using photoexcited triplet states. We study homonuclear and heteronuclear fullerene derivatives and we identify in each case the relevant parameters that can lead to high fidelity entangling operations. The hyperfine interaction in a homonuclear system is the key parameter which determines the degree of entanglement between the nucelar spins according to a recent theoretical proposal. We measure and calculate the hyperfine interaction in homonuclear systems with 13C nuclear spins in order to prove the feasibility of this scheme. Further experiments on a fullerene system with two nuclear spins a 31P and a 1H show that entangling operations of high fidelity which involve the demonstration of CNOT gates, are possible within the lifetime of the triplet state.</p
Entangling nuclear spins using photoexcited triplet states
Entanglement is one of the most technologically important quantum phenomena and its con-trolled creation brings us a step closer to the realisation of a quantum computer. Hybrid electron and nuclear spin systems which combine long nuclear decoherence times with the high polarisation and rapid processing times of electron spins are considered reliable candidates for the representation of the fundamental building block of a quantum computer, the qubit. In the literature electron spins quite often play the role of a mediator which can access, manipulate and couple states with long coherence times, beneficial for storing quantum information.
Despite the fact that an electron spin can be a useful resource for nuclear spin systems, its permanent presence can be a source of decoherence. The use of transient photoexcited electron spins provide an additional advantage and once the operations which involve the electron spin are completed, the electron spin can decay and not interfere further with the evolution of the system.
In this thesis we report magnetic resonance experiments and density functional theory calculations for the demonstration of nuclear - nuclear entanglement using photoexcited triplet states. We study homonuclear and heteronuclear fullerene derivatives and we identify in each case the relevant parameters that can lead to high fidelity entangling operations.
The hyperfine interaction in a homonuclear system is the key parameter which determines the degree of entanglement between the nucelar spins according to a recent theoretical proposal. We measure and calculate the hyperfine interaction in homonuclear systems with 13C nuclear spins in order to prove the feasibility of this scheme. Further experiments on a fullerene system with two nuclear spins a 31P and a 1H show that entangling operations of high fidelity which involve the demonstration of CNOT gates, are possible within the lifetime of the triplet state.This thesis is not currently available in OR