Education

Ph.D., Nuclear Science and Engineering, Massachusetts Institute of Technology, 2006
M.S., Applied Physics, École Centrale Paris, 2000
B.S/M.S., Nuclear Engineering, Politecnico di Milano, 2000

Teaching

Quantum Theory of Radiation Interactions (22.51)
Introduction to Applied Nuclear Physics (22.02)

Research

The development of new technologies at scales approaching the quantum regime is driving new theoretical and experimental research on control in quantum systems. The implementation of quantum control would have an enormous impact on a wide range of fields such as chemistry, nuclear magnetic resonance, microelectronics, and precision metrology. Quantum control finds an ideal application in quantum information processing (QIP), which promises to radically improve the acquisition, transmission, and processing of information. To reach this goal it is necessary to improve both the experimental techniques and the coherent control theory of quantum bits (qubits), as well as to gain a deeper knowledge of the mechanisms of decoherence, which must be studied and fought against.

The main topics of my research are methods of control of physical systems that can deliver QIP devices (not only quantum computers but also simulators, measuring and communication devices, etc.), which exceed the capacities of the corresponding classical devices.

These ideas will be explored experimentally in the setting of magnetic resonance, where control techniques have a long tradition. A system that has emerged as a unique candidate for QIP is the Nitrogen-vacancy (NV) center in diamond. The NV electronic spin can be optically polarized and measured; nearby nuclear and electronic spins are manipulated via magnetic resonance techniques. These small quantum systems can thus be used as building blocks for larger QIP architectures or as task-oriented nanoscale quantum devices (such as simulators or sensors). The strength of this system is in a hybrid approach that combines ideas from quantum optics, mesoscopic physics, and magnetic resonance. Larger spin systems will be instead explored via solid-state NMR techniques. Applications are in the simulations of complex many-body systems and quantum information transport.

These experimental efforts will be accompanied by theoretical investigation of the coherent control of open quantum systems: from advanced techniques for optimal control, which yield more efficient schemes and avoid decoherence effects, to mappings of known control strategies to the characteristics of a given system and its environment.

Figure 1: The Nitrogen-Vacancy center in diamond. Left: isolated defect center in the diamond crystal. Right: optical and microwave control of the NV energy levels.

Figure 2: Schematic for a nano scale diamond-based spin magnetometer. A Nitrogen-Vacancy center implanted on a nanodiamond on a scanning tip can measure magnetic fields with high sensitivity and high spatial resolution.

Awards

• Graduate Teaching Award, MIT School of Engineering (2005)
• Manson Benedict Fellowship (MIT Department of Nuclear Science and Engineering, 2004)
• Outstanding Teaching Assistant Award (MIT Department of Nuclear Science and Engineering, 2002)
• Alpha Nu Sigma
• Fondazione Famiglia Legnanese Fellowship (Milan, 1998)

Selected Publications

1. P. Cappellaro, M. Lukin "Quantum correlation in disordered spin systems: entanglement and applications to magnetic sensing" arXiv:0904.2642, to appear in Phys. Rev. A (2009)
2. P. Cappellaro, L. Jiang, J. S. Hodges, M. D. Lukin, "Coherence and Control of Quantum Registers Based on Electronic Spin in a Nuclear Spin Bath", Phys. Rev. Lett. 102, 210502 (2009)
3. P. Rabl, P. Cappellaro, M. V. Gurudev Dutt, L. Jiang, J. R. Maze, M. D. Lukin, "Strong magnetic coupling between an electronic spin qubit and a mechanical resonator", Phys. Rev. B 79, 041302 (R) (2009)
4. J. M. Taylor, P. Cappellaro, L. Childress, L. Jiang, D. Budker, P. R. Hemmer, A. Yacoby, R. Walsworth, M. D. Lukin "High-sensitivity diamond magnetometer with nanoscale resolution" Nature Phys. 4, 810-816 (2008)
5. J. R. Maze, P. L. Stanwix, J. S. Hodges, S. Hong, J. M. Taylor, P. Cappellaro, L. Jiang, M. V. G. Dutt, E. Togan, A.S. Zibrov, A. Yacoby, R. L. Walsworth, M. D. Lukin, "Nanoscale magnetic sensing with an individual electronic spin in diamond" Nature 455, 644 - 647 (2008)
6. P. Cappellaro, C. Ramanathan and D. G. Cory "Simulations of Information Transport in Spin Chains", Phys. Rev. Lett. 99, 250506 (2007)
7. P. Cappellaro, J. Emerson, N. Boulant, C. Ramanathan, S. Lloyd and D. Cory "Entanglement Assisted Metrology", Phys. Rev. Lett. 94(2), 20502 (2005)