Personal Homepages

• Holliday Prize, Institute of Materials, 1984
• Metrology award for World Class Manufacturing, 1999
• Honorary Fellow of Royal Microscopical Society, 2000

Synthesis and characterization of dimers for quantum entanglement
G. Liu, Dr. K. Porfyrakis, Dr. A.N. Khlobystov*, Dr. A. Ardavan**, Professor G.A.D. Briggs
The fabrication of asymmetric dimers of endohedral fullerenes containing nitrogen atoms will enable spin resonance experiments to be performed that demonstrate entanglement between electron spins. This will constitute a crucial proof of principle of controlled entanglement in carbon nanomaterials. Chemical synthesis routes will be used that preserve the delicate endohedral nitrogen species, including the use of metal atoms to join the fullerenes through metal coordination bonds or via functionalising groups. (*University of Nottingham; **Clarendon Laboratory, Department of Physics)

Endohedral fullerene derivatives for Quantum Information Processing
B.J. Farrington, Dr. M. Jevric, Dr. A. Ardavan**, Professor G.A.D. Briggs, Dr. K. Porfyrakis
Using new high-throughput purification technologies it is now possible to produce high purity N@C60 samples on a sufficiently large scale to allow chemical functionalization of the fullerene cage. We are developing the chemistry of endohedral fullerenes with the aim of synthesizing initially dimeric and subsequently oligomeric chains of spin-active molecules. We shall control the distance between endohedral fullerenes by designing appropriate bridge molecules with varying length. We shall develop the ability to engineer and manipulate spin-spin interactions along these chains. A molecular structure of this kind could constitute a key building block for any technology based on information processing with electron spins. (**Clarendon Laboratory, Department of Physics)

Entanglement in spin ensembles
S. Simmons, R.M. Brown, Professor G.A.D. Briggs, Dr. A. Ardavan*, Dr. J.J.L. Morton
Quantum Information Processing critically relies upon powerful 'entangled' quantum states to outperform classical information technology. Such states have yet to be created in qubits made of spin ensembles, including collections of N@C60 molecules and defect donors in semiconductors. We are working towards creating entangled states out of highly polarized nuclear and electronic qubit ensembles controlled by ESR (Electron Spin Resonance). For this we have developed full density matrix tomography techniques to faithfully read out all the information contained within an arbitrary quantum state. We have also developed optimized control techniques to generate the most entanglement from these systems. (*Clarendon Laboratory)

Electrically Detected Magnetic Resonance in Semiconductor and Carbon Nanodevices
V. Lang, Dr. R.E. George, Dr. A. Ardavan*, Dr. J.J.L. Morton, Professor G.A.D. Briggs
Electrically Detected Magnetic Resonance (EDMR) is used to investigate electron spin dynamics in semiconductor and carbon nanodevices and to evaluate the interaction between conduction electrons and paramagnetic defect states with respect to applications for quantum information processing. The measurement setup developed within this work permits EDMR experiments at low (X-band) and high magnetic fields (W-band). Initial results have been obtained on amorphous hydrogenated silicon solar cells as well as arsenic and antimony doped silicon field-effect transistors.   (*Dept. of Physics, Oxford University, UK. This work also involves collaborations with the University of California, Berkeley, USA, Lawrence Berkeley National Laboratory, USA, Princeton University, USA, and University of New South Wales, Australia.) (Funded by EPSRC, Konrad-Adenauer-Stiftung e.V. and CAESR.)

Pulsed magnetic resonance in photoexcited triplet states
V. Filidou, Dr. J.J.L. Morton, Dr. F. Giustino, Dr. A. Ardavan*, Professor G.A.D. Briggs
The challenge of this project is to identify molecules that exhibit long decoherence times when nuclear spins are coupled to transient electron spins. The key parameter that determines the interaction between electron and nuclear spins, the hyperfine interaction, is measured in several fullerene derivatives using EPR techniques. In order to gain a better understanding of the experimental results first principal calculations are performed within the density functional theory (DFT). (*Clarendon Laboratory)

Dimers for quantum computing
Dr. K. Porfyrakis, Dr. A. Ardavan*, Professor G.A.D. Briggs
Electron spin active dimers could be used to realize a two-qubit system for quantum computing. We have synthesized directly bonded empty fullerene dimers by high speed vibration milling. The same method can be used to synthesize endohedral fullerene dimers to realize a two-qubit system. We are investigating the switchable dimers for a controllable two-qubit system. We are synthesizing azobenzene bridged nitroxyl free radical dimers and fullerene dimers. UV/Vis light can be used to switch the bridge from trans- to cis-, or vice verse, in order to control the qubit interaction, which can be probed by ESR method. (*Clarendon Laboratory, Department of Physics)

Manufacture of HPLC Columns for Separation of N@C60
Dr. A.N. Khlobystov*, Dr. K. Porfyrakis, Dr. A. Ardavan**, Professor G.A.D. Briggs
N@C60 and C60 are difficult to separate, as they have virtually indistinguishable affinities for most materials. We have targeted their most apparent difference, mainly that N@C60 is more polarizable than C60, to facilitate separation of the two molecules. We are designing materials that have exceptionally large polarizabilities and attaching them to silica for use as packing material for high performance liquid chromatography columns.(*University of Nottingham; **Clarendon Laboratory, Department of Physics)

Electron spin resonance of fullerene materials at low magnetic fields
T. Poulianitis, Dr. R.E. George, Dr. J.J.L. Morton, Dr. A. Ardavan*, Professor G.A.D. Briggs
A low field CW spectrometer operating in the range 10 MHz to 1 GHz and a series of resonators are developed in order to experimentally investigate the atomic clock transition in the 15N@C60 molecule and the challenges and practical considerations associated with the EPR instrumentation in the low field regime. The energy levels and energy differences of the 15N@C60 molecule at low magnetic fields (0-20 Gauss) are calculated to reveal the potential of using this system as a high stability frequency standard. An operating point is identified at which the splitting of an 'atomic clock' transition has no first-order dependence on the magnetic field. The energy difference of this level pair is therefore insensitive to fluctuations in the magnetic environment that typically limit the accuracy to which EPR transition frequencies can be measured at low magnetic fields, and forms the basis for our frequency standard scheme. Further research pursued with the spectrometer includes sensitive low field ODMR and ESR of phosphorus doped silicon at low magnetic fields (*Department of Physics)

Supramolecular structures for nanoelectronics and quantum computing
Professor M.R. Castell, Professor G.A.D. Briggs, Dr. A. Ardavan*, Dr. S.C. Benjamin, Dr. K. Porfyrakis
Conventional lithographic techniques for surface patterning have powered technological progress for decades and can now reach dimensions down to 20-30 nm. We shall pursue a fundamentally different approach to templating based on a 'bottom-up' nanotechnology in which nanoscale building blocks spontaneously adopt an ordered configuration through a self-assembly process. We shall use these templates to create structures suitable for nanoelectronics and quantum computing. The primary approach will be deposition of a passive molecular 'scaffolding' followed by subsequent deposition of a molecular species that forms an ordered distribution within that scaffolding. The species employed will be an endohedral fullerene with the property that the encapsulated atom can store information in the state of its nuclear and/or electron spin. In this way we shall create ordered arrays of quantum bits (qubits). Experiments will be designed to characterise the qubit-qubit intereactions, and the results will be used to guide further generations of nanoarray synthesis, with the ultimate goal of creating structures suitable for information processing. (*Department of Physics)

Modelling the formation of hydrogen-bonded molecular networks on crystalline surfaces
U. Weber, Dr. V. Burlakov, Professor D.G. Pettifor, Professor J.H. Jefferson*, Professor G.A.D. Briggs
The main objective is to develop a model suitable for simulation of hydrogen-bonded molecular networks on crystalline surfaces taking into account a mismatch between the crystal structures of the surfaces and the molecular network. An important part of the project is related to the development of environment-dependent potential describing hydrogen bonds between the network-forming molecules. This potential will then be used in kinetic MC simulations to guide experimental studies of the molecular networks and the structures suitable for QIP on different substrates. The potential parameters will be extracted using ab initio calculations performed in collaboration with L. Kantorovich (King's College, London), and verified against experimental studies carried out in the groups of P. Beton and N. Champness (Nottingham University). (*QinetiQ).(Funded by EPSRC).

Endohedral Fullerenes for Quantum Information Processing
Dr. J.J.L. Morton, Dr. K. Porfyrakis, Dr. A.M. Khlobystov*, Dr. A. Ardavan**, Professor G.A.D. Briggs
One of the most remarkably robust examples of an unpaired electron spin within a molecule is that of a nitrogen atom trapped inside a spherical fullerene (termed N@C60). We have measured the coherence time of a qubit encoded within this electron spin system and performed single qubit operations using pulsed electron paramagnetic resonance (EPR). We are investigating the synthesis of several types of endohedral fullerene dimers including directly-bonded and oxygen-bridged dimers. These multi-qubit systems will then be characterised by EPR. We shall study the ability to control qubit interactions through the inter-fullerene bridge, and move on to investigate larger qubit arrays. (*University of Nottingham; **Clarendon Laboratory, Department of Physics)

Molecules inside Nanotubes: a Synergistic Host-Guest System
Dr. A.N. Khlobystov*, Dr. K. Porfyrakis, Professor G.A.D. Briggs, Dr. A. Ardavan*, Professor R.J. Nicholas*
We are exploring interactions between carbon nanotubes and various organic and organometallic molecules, including fullerenes. These nanostructures demonstrate unique synergistic host-guest properties. Structural and dynamic behaviour of the encapsulated molecules is substantially affected by confinement in the nanotube and is mainly controlled by geometrical parameters of the host. Complementarily, the mechanical and electronic properties of the tubular host are influenced by the guest molecules due to the coupling between the molecular orbitals of the guest and the electronic bands of the nanotube. Host-guest systems of this type exhibit a range of functional properties which can be exploited in chemistry and nanotechnology. (*University of Nottingham; **Clarendon Laboratory, Department of Physics)

Electron spin ensemble based multimode quantum memory
H. Wu, Dr. J.J.L. Morton, Dr. A. Ardavan *, Professor G.A.D. Briggs
Ensembles of electron spin could be used as the media for quantum memory by utilizing the principle of holographic information storage. Multiple spatial phase modes are created by applying magnetic field gradient to the spin ensembles, in which multiple units of information are stored. The use of pulsed magnetic field gradients allows us to get access to the stored information selectively. This type of multimode quantum memory, in combination with superconducting qubit and cavity, could be used to develop a hybrid model of quantum computer. (*Clarendon Laboratory, Department of Physics)

13 public active projects

Publications since 1/1/2009 are listed below. For more information see Full List of Publications.

Spin lifetimes in quantum dots from noise measurements. Phys. Rev. Lett. 102, 016802 (2009); DOI: 10.1103/PhysRevLett.102.016802. J. Wabnig, B.W. Lovett, J.H. Jefferson and G.A.D. Briggs.

Polyarene-functionalized fullerenes in carbon nanotubes: towards controlled geometry of molecular chains. Small 4, 2262-2270 (2008); DOI: 10.1002/smll.200800552. T.W. Chamberlain, R. Pfeiffer, H. Peterlik, H. Kuzmany, F. Zerbetto, M. Melle-Franco, L. Staddon, N.R. Champness, G.A.D. Briggs and A.N. Khlobystov.

Atomic clock. International Patent Application No. PCT/GB008/002229; Pub. No. WO/2009/004317 (08.01.2009). G.A.D. Briggs and A. Ardavan.

Direct imaging of rotational stacking faults in few layer graphene. Nano Lett. 9, 102-106 (2009); DOI: 10.1021/nl8025949. J.H. Warner, M.H. Rümmeli, T. Gemming, B. Büchner and G.A.D. Briggs.

Scattering-induced entanglement between spin-qubits at remote two-state structures J. Phys.: Condens. Matter 21, 075503 (2009); DOI: 10.1088/0953-8984/21/7/075503. M. Habgood, J.H. Jefferson and G.A.D. Briggs.

Effects of doping on electronic structure and correlations in carbon peapods. ACS Nano 3, 1069-1076 (2009, published online 7 April); DOI: 10.1021/nn8008454. L. Ge, J.H. Jefferson, B. Montanari, N.M. Harrison, D.G. Pettifor and G.A.D. Briggs.

And information became physical. In Real Scientists, Real Faith (ed R. J. Berry) pp. 72-84, Lion Hudson (2009); ISBN: 978-1-85424-884-8. G.A.D. Briggs. §

One-dimensional confined motion of single metal atoms inside double-walled carbon nanotubes. Phys. Rev. Lett. 102, 195504 (2009); DOI: 10.1103/PhysRevLett.102.195504. J.H. Warner, Y. Ito, M.H. Rümmeli, T. Gemming, B. Büchner, H. Shinohara and G.A.D. Briggs.

Magnetic field sensing beyond the standard quantum limit using 10-spin NOON states. Science 324, 1166-1168 (2009, published online 23 April); DOI: 10.1126/science.1170730. J.A. Jones, S.D. Karlen, J. Fitzsimons, A. Ardavan, S.C. Benjamin, G.A.D. Briggs and J.J.L. Morton. Reported in Electronics Weekly 29 April - 5 May 2009, p. 7; This Week in Science 29 May 2009, p. 1115.

And information became physical. The Reader 106, 14-15 (2009); abridged chapter from Real Scientists, Real Faith. G.A.D. Briggs. §

Investigating the diameter-dependent stability of single-walled carbon nanotubes. ACS Nano 3, 1557-1563 (2009, published online 22 May); DOI: 10.1021/nn900362a. J.H. Warner, F. Schaffel, G. Zhang, M.H. Rümmeli, B. Büchner, J. Robertson and G.A.D. Briggs. Nanowerk Spotlight 25 June 2009 www.nanowerk.com/spotlight/spotid=11356.php.

A bimetallic endohedral fullerene. Chem. Commun. 27, 4082-4084 (2009); DOI: 10.1039/b902520k. S.R. Plant, T.C. Ng, J.H. Warner, G. Dantelle, A. Ardavan, G.A.D. Briggs and K. Porfyrakis.

Acuminated fluorescence of Er³⁺ centres in endohedral fullerenes through the incarceration of a carbide cluster Chem. Phys. Lett. 476, 41-45 (2009); DOI: 10.1016/j.cplett.2009.05.042. S.R. Plant, G. Dantelle; Y. Ito; T.C. Ng; A. Ardavan; H. Shinohara, R.A Taylor, G.A.D. Briggs, K. Porfyrakis.

Structural transformation of graphene studied with high spatial and fast temporal resolution. Nature Nanotech. 4, 500-504 (2009, published online 2 August); DOI: 10.1038/nnano.2009.194. J.H. Warner, M.H. Rümmeli, L. Ge, T. Gemming, B. Montanari, N.M. Harrison, B. Büchner and G.A.D. Briggs. Reported in Graphene Times 2 August 2009 graphenetimes.com.

Cryogenic instrumentation for fast current measurement in a silicon single electron transistor. J. Appl. Phys. 106, 033705 (2009, published online 7 August); DOI: 10.1063/1.3191671. T. Ferrus, D.G. Hasko, Q.R. Morrissey, S.R. Burge, E.J. Freeman, M.J. French, A. Lam, L. Creswell, R.J. Collier, D.A. Williams and G.A.D. Briggs.

Quantum computing with an electron spin ensemble. Phys. Rev. Lett. 103, 070502 (2009, published online 11 August); DOI: 10.1103/PhysRevLett.103.070502. J.H. Wesenberg, A. Ardavan, G.A.D. Briggs, J.J.L. Morton, R.J. Schoelkopf, D.I. Schuster and K. Mølmer. Reported in PhysOrg 9 September 2009 www.physorg.com/news171705608.html.

Optical properties of Er³⁺ in fullerenes and in β-PbF₂ single-crystals. Optical Materials 32, 251-256 (2009, published online 22 August); DOI: 10.1016/j.optmat.2009.07.021. G. Dantelle; A. Tiwari, R. Rahman, S.R. Plant, K. Porfyrakis, M. Mortier, R.A. Taylor and G.A.D. Briggs.

Acoustic Microscopy: Fundamentals and Applications By Roman Gr. Maev. Physics Today 62 (10) 59-60 (October 2009). G.A.D. Briggs. §

Capturing the motion of novel molecular nanomaterials encapsulated within carbon nanotubes with ultrahigh temporal resolution. ACS Nano 3, 3037-3044 (2009); DOI: 10.1021/nn900747r. J.H Warner, Y. Ito, M.H. Rümmeli, B. Büchner, H. Shinohara and G.A.D. Briggs.

Erratum: Efficient Dynamic Nuclear Polarization at High Magnetic Fields [Phys. Rev. Lett. 98, 220501 (2007)]. Phys. Rev. Lett. 103, 199902(E) (2009); DOI: 10.1103/PhysRevLett.103.199902. G.W. Morley, J. van Tol, A. Ardavan, K. Porfyrakis, J. Zhang and G.A.D. Briggs.

Introduction to Nanoscience and Nanotechnology By Gabor L. Hornyak, Harry F. Tibbals, Joydeep Dutta, John J. Moore. Times Higher Education 1925, xii (3 December 2009). G.A.D. Briggs. §

A closer look at the hidden world. No Small Matter: Science on the Nanoscale By Felice C. Frankel and George M. Whitesides. Times Higher Education, 1926, 50 (10 December 2009). G.A.D. Briggs. §

Investigations of N@C₆₀ and N@C₇₀ stability under high pressure and high temperature conditions. Phys. Stat. Sol. B 246, 2767-2770 (2009); DOI: 10.1002/pssb.200982270. A. Iwasiewicz-Wabnig, K. Porfyrakis, G.A.D. Briggs and B. Sundqvist.

H-bonding supramolecular assemblies of PCDI molecules on the Au(111) surface. J. Phys. Chem. C 113, 21840-21848 (2009); DOI: 10.1021/jp908046t. M. Mura, F. Silly, G.A.D. Briggs, M.R. Castell and L.N. Kantorovich.

Single shot measurement of a silicon single electron transistor. Proc. 9^th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology, 317-320 (2009); ISBN: 978-981-4282-12-3. D.G. Hasko, T. Ferrus, Q.R. Morrissey, S.R. Burge, E.J. Freeman, M.J. French, A. Lam, L. Creswell, R.J. Collier, D.A. Williams and G.A.D. Briggs.

Scanning tunnelling microscopy studies of C₆₀ monolayers on Au(111). Phys. Rev. B 80, 235434 (2009); DOI: 10.1103/PhysRevB.80.235434. J.A. Gardener, G.A.D. Briggs and M.R. Castell.

Endohedral metallofullerenes in self-assembled monolayers. Phys. Chem. Chem. Phys. 12, 123-131 (2010, published online 11 November 2009); DOI: 10.1039/b915170b. M.C. Gimenez-Lopez, J. Gardener, A. Iwasiewicz-Wabnig, K. Porfyrakis, C. Balmer, G. Dantelle, A.Q. Shaw, M. Hadjipanayi, A. Crossley, N.R. Champness, M.R. Castell, G.A.D. Briggs and A.N. Khlobystov.

Controlling intermolecular spin interactions of La@C₈₂ in empty fullerene matrices. Phys. Chem. Chem. Phys. 12, 1618-1623 (2010); DOI: 10.1039/b913593f. Y. Ito, J.H. Warner, R. Brown, M. Zaka, R. Pfeiffer, T. Aono, N. Izumi, H. Okimoto, J.J.L. Morton, A. Ardavan, H. Shinohara, H. Kuzmany, H. Peterlik and G.A.D. Briggs.

Nanoethics: Big Ethical Issues with Small Technology, By Dónal P. O’Mathúna. Times Higher Education 1935, 48-49 (18-24 February 2010); www.timeshighereducation.co.uk/story.asp‌storycode=410398. G.A.D. Briggs. §

Exchange interactions of spin-active metallofullerenes in solid-state carbon networks. Phys. Rev. B 81, 075424 (2010, published online 22 February); DOI: 10.1103/PhysRevB.81.075424. M. Zaka, J.H. Warner, Y. Ito, J.J.L. Morton, M.H. Rümmeli, T. Pichler, A. Ardavan, H. Shinohara and G.A.D. Briggs.

Intricate hydrogen-bonded networks: binary and ternary combinations of uracil, PTCDI and melamine. J. Phys. Chem. C 114, 5859-5866 (2010); DOI: 10.1021/jp9113249. J.A. Gardener, O.Y. Shvarova, G.A.D. Briggs and M.R. Castell.

Magnetic field sensing using a driven double quantum dot. Physica E 42, 895-898 (2010); DOI: 10.1016/j.physe.2009.11.138. G. Giavaras, J. Wabnig, B.W. Lovett, J. H. Jefferson and G.A.D. Briggs.

Experimental and theoretical analysis of H-bonding supramolecular assemblies of PTCDA molecules. Phys. Rev. B 81, 195412 (2010); DOI: 10.1103/PhysRevB.81.195412. M. Mura, X. Sun, F. Silly, H.T. Jonkman, G.A.D. Briggs, M.R. Castell and L.N. Kantorovich.

Entangling remote nuclear spins linked by a chromophore. Phys. Rev. Lett. 104, 200501 (2010); DOI: 10.1103/PhysRevLett.104.200501. M. Schaffry, V. Filidou, S.D. Karlen, E.M. Gauger, S.C. Benjamin, H.L. Anderson, A. Ardavan, G.A.D. Briggs. K. Maeda, K.B. Henbest, F. Giustino, J.J.L. Morton and B.W. Lovett.

Ultrahigh secondary electron emission of carbon nanotubes. Appl. Phys. Lett. 96, 213113 (2010, published online 27 May); DOI: 10.1063/1.3442491. J. Luo, J.H. Warner, C. Feng, Y. Yao, Z. Jin, H. Wang, C. Pan, S. Wang, L. Yang, Y. Li, J. Zhang, A.A.R. Watt, L.M. Peng, J. Zhu and G.A.D. Briggs.

Single shot measurement in silicon single electron transistors. 2008 IEEE Silicon Electronics Workshop, 32-33 (2008); IDS Number: BPK87; ISBN: 978-1-4244-2071-1. T. Ferrus, D.A. Williams, D.G. Hasko, L. Creswell, R.J. Collier, A. Lam, Q.R. Morrissey, S.R. Burge, M.J. French and G.A.D. Briggs.

Electron spin coherence in metallofullerenes: Y, Sc and La@C₈₂. Phys. Rev. B 82, 033410 (2010); DOI: 10.1103/PhysRevB.82.033410. R.M. Brown, Y. Ito, J.H. Warner, A. Ardavan, H. Shinohara, G.A.D. Briggs and J.J.L. Morton.

Direct imaging and chemical identification of the encapsulated metal atoms in bimetallic endofullerene peapods. ACS Nano 4, 3943-3948 (2010); DOI: 10.1021/nn100823e. R.J. Nicholls, K. Sader, J.H. Warner, S.R. Plant, K. Porfyrakis, P.D. Nellist, G.A.D. Briggs and D.J.H. Cockayne.

A cyclic porphyrin trimer as a receptor for fullerenes. Org. Lett. (2010, published online 2 July); DOI: 10.1021/ol101393h. G. Gil-Ramírez, S.D. Karlen, A. Shundo, K. Porfyrakis, Y. Ito, G.A.D. Briggs J.J.L. Morton and H.L. Anderson.

Spin detection at elevated temperatures using a driven double quantum dot. Phys. Rev. B 82, 085410 (2010, published online 6 August); DOI: 10.1103/PhysRevB.82.085410. G. Giavaras, J. Wabnig, B.W. Lovett, J.H. Jefferson and G.A.D. Briggs. Selected for the August 23, 2010 issue of Virtual Journal of Nanoscale Science & Technology, www.vjnano.org.

Book of the Week: Science vs. Religion: What Scientists Really Think. Times Higher Education (16 September 2010); www.timeshighereducation.co.uk/story.asp‌sectioncode=26&storycode=413457&c=1. G.A.D. Briggs. §

High cooperativity coupling of electron-spin ensembles to superconducting cavities. Phys. Rev. Lett. 105, 140501 (2010, published online 27 September). D.I. Schuster, A.P. Sears, E. Ginossar, L. DiCarlo, L. Frunzio, J.J.L. Morton, H. Wu, G.A.D. Briggs and R.J. Schoelkopf. Featured in Viewpoint PhysRevLett.105.140503.

Storage of multiple coherent microwave excitations in an electron spin ensemble. Phys. Rev. Lett. 105, 140503 (2010, published online 27 September). H. Wu, R.E. George, A. Ardavan, J.H. Wesenberg, K. Mølmer, D.I. Schuster, R.J. Schoelkopf, K.M. Itoh, J.J.L. Morton and G.A.D. Briggs. Featured in Viewpoint PhysRevLett.105.140503.

High performance field effect transistors from solution processed carbon nanotubes. ACS Nano (2010, published online 19 October); DOI: 10.1021/nn1020743, http://pubs.acs.org/doi/pdf/10.1021/nn1020743. H. Wang, J. Luo, A. Robertson, Y. Ito, W. Yan, V. Lang, M. Zaka, F. Schäffel, M. Rümmeli, G.A.D. Briggs and J.H. Warner.

Nanomaterials for quantum information processing
GAD Briggs / A Ardavan (Department of Physics) / JJL Morton / K Porfyrakis / JH Warner

Quantum information processing offers one of the most exciting challenges in the study and development of nanomaterials. It is at the cutting edge of quantum nanoelectronics, and we are part of the world wide race to develop a scalable quantum computer. We need materials with quantum states that can be individually controlled and measured, and yet which are sufficiently robust against decoherence that they can sustain a sequence of quantum manipulations and interactions. We lead the world in using the new family of fullerene materials (popularly known as Bucky balls), which can be used to contain atomic and molecular species inside a cage that separates them from the quantum environment. We can insert fullerenes into carbon nanotubes to create one-dimensional 'peapod' arrays, which we can image by HRTEM, and we are also developing other schemes for molecular self-assembly of fullerenes and other functional molecules. We can also use other materials such as doped silicon and diamond. We can store the quantum information in electron or nuclear spin, and exchange it between the two. We can manipulate and characterize the spin states by electron paramagnetic resonance and also optically. By creating entanglement between several spins, it will be possible to develop sensors that exceed the standard quantum limit. By storing information holographically in collective spin states, it will be possible to process quantum information in large ensembles of spins. There will be several projects with these nanomaterials, ranging from synthesis and characterization to experimental implementation of candidate schemes for quantum computing. The research is highly interdisciplinary, and there is scope for a range of skills and interests from materials science and chemistry to experimental quantum physics (qsd.materials.ox.ac.uk). In association with the experimental programme which will take place within a large and active research group (www.qipirc.org), there will be theory and modelling projects with Dr S C Benjamin, Dr J Fitzsimons, Dr B W Lovett and Professor J H Jefferson (www.qunat.org). There may be possibilities for industrial support and for international travel and collaboration.

Also see homepages: Andrew Briggs John Morton Kyriakos Porfyrakis Jamie Warner

Endohedral metallofullerenes for nanotechnological applications
K Porfyrakis / G A D Briggs

Fullerenes are fascinating carbon-based materials. Their most interesting feature is that due to their cage-like structure they can trap atom(s) inside their empty "shell". This project explores the synthesis and chemical functionalization of endohedral metallofullerenes: Mn@Cm (where n=1-3 and m ≥ 60).
We shall synthesise novel endohedral metallofullerenes using a new arc-discharge facility. We shall customise the fullerene molecular structure in order to tune their properties, such as their HOMO-LUMO gap. We shall develop methods for the covalent functionalization of endohedral metallofullerenes. We shall investigate the effect of rigid or flexible functional groups on the electronic properties of the endohedral species. We shall focus on malonate and pyrrolidine adducts initially, but other schemes will also be considered. Endohedral metallofullerenes and their derivatives will be purified by high-performance liquid chromatography (HPLC) and will be characterized by various spectroscopic techniques available to us, including mass spectrometry, UV-Vis-NIR and FTIR spectroscopies and other analytical tools.
These nanomaterials are of interest for quantum information processing, but are also attractive for opto-electronics and photovoltaic applications.

Also see homepages: Andrew Briggs Kyriakos Porfyrakis

Also see a full listing of New projects available within the Department of Materials.