Topical Group: Quantum Computing

October 6 - October 17, 2008
Cambridge, Ma 02138


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This topical group, extending over two weeks, will bring together a select number of practitioners in the field of Quantum Information Science, Adiabatic Quantum Computing, as well as the interface between Atomic Physics, Quantum Optics, and Condensed Matter Physics. The dates are Oct. 6-17. There will be a small number of talks (1-2) a day and ample time for discussions and interactions.

Schedule:

Mon. Oct. 6

10:00am - 2:00pm, Pratt Conference Room, CfA

2:00pm - 6:00pm, LISE 303, Harvard Physics

Tues. Oct. 7

10:00 am - LISE 319

Xuedong Hu - Univ. of Buffalo and RIKEN
Semiconducting Qubits

2:00 pm - LISE 303

Edward Laird - Harvard
"Hyperfine-mediated gate-driven electron spin resonance"

Other rooms reserved for informal meeting:
10:00 am - 12:00 am, Lyman 330, Harvard Physics and 11:30am - 3:00pm, Tea Room, CfA

Wed. Oct 8

10:00 am - Tearoom - Center for Astrophysics

Sahel Ashhab, Digital Materials Laboratory- RIKEN
"Quantum non-locality of a single delocalized particle"

2:00pm - LISE 303, Harvard Physics

Hendrik Bluhm (Harvard) Title TBD

Joint Atomic Physics Colloquium
4:30 pm - Dave Cory (MIT), "Error Finding and Control for Quantum Processors"
Jefferson Lab 356

Other rooms reserved for informal meeting:
10:00am - 12:30pm, Phillips Auditorium, CfA

Other rooms reserved: 10:30-12:30 Phillips

Thurs. Oct 9

 

10:00 am - 1:00pm Meeting Room C-34

Dr. William D. Oliver, MIT Lincoln Laboratory, Analog Device Technology Group
"Amplitude spectroscopy of a superconducting artificial atom"

Dr. Jonas Bylander, MIT Research Laboratory of Electronics, Superconducting Circuits and Quantum Computation Group, MIT
" Pulse calibration and non-adiabatic control of a superconducting artificial atom"

2:00 pm - LISE 303, Harvard Physics

Jimmy Williams (Harvard)
"The Effect of p-n Junctions on Mesoscale Transport in Graphene"

3:00 pm

Jeff Miller (Harvard)
“Quasiparticle Properties from Tunneling in the nu = 5/2 Fractional Quantum Hall State”

 

Fri. Oct 10

 

The Harvard University Center for Nanoscale Systems (CNS) and the National Nanotechnology Infrastructure Network announce (NNIN) a one day workshop: Photosynthesis – from Elementary Processes to Quantum SimulationDivision Room - M102 in Mallinckrodt, 12 Oxford Street from 9am-4pm

For More Information Regarding this one day workshop, please contact, Anna B Shin, Group Administrator, Department of Chemistry and Chemical Biology, 617-496-9964. or online at http://cns.fas.harvard.edu/about/docs/photosynthesis.pdf

Other rooms reserved: 10:30-2:00 Pratt

 

Mon. Oct 13

 

10 am: Dr. Sekhar Ramanathan, MIT Title: NMR studies of quantum information processes

 

4:30 pm: Frank Gaitan, RIKEN and Univ. of S. Illinois: Density functional theory and quantum computation

Abstract: We demonstrate the applicability of ground-state and time-dependent density functional theory to quantum computing by proving the Hohenberg-Kohn and Runge-Gross theorems for a fermion system representing N qubits. Time-dependent density functional theory is used to determine the minimum energy gap Delta(N) arising from application of the quantum adiabatic evolution algorithm to the NP-Complete problem MAXCUT. As density functional theory has been used to treat quantum systems with as many as 650 interacting degrees of freedom, this raises the realistic prospect of evaluating the gap Delta(N) for systems with N ~ 650 qubits.

Ref. F. Gaitan and F. Nori, Density functional theory and quantum computation, arXiv:0809.1170v1 [quant-ph]

 

Tues. Oct 14

10:00am - 11:00am, Pratt, CfA

"Quantum control of spins in diamond"
Paola Cappellaro, ITAMP

Nitrogen-Vacancy (NV) centers in diamond have emerged as excellent candidates for quantum information processing, since they can be optically polarized and detected, and present good coherence properties even at room temperature. In this talk I will present the application of coherent control techniques to the electronic and nuclear spins associated with NV centers.
I will first show how this solid state system can be used as the building block of a scalable architecture for quantum computation or communication, and present potential strategies for the efficient control of these small quantum registers.
Then I will present a novel approach to magnetometry, based on NV centers, that takes advantage of coherent control techniques and the confinement of the sensing spins into a sample of nanometer dimensions. The resulting magnetic sensor is projected to yield an unprecedented combination of high sensitivity and spatial resolution, with the potential of exciting applications in bio-science, materials science, and single electronic and nuclear spin detection.

11:00 am - 12:00 noon, Pratt CfA

Jero Maze, "Nanoscale magnetic sensing using a single electron spin in
diamond"

 

3:00 pm Tearoom, CfA: Dr. Toshiaki Iitaka, RIKEN: Title: Large-scale simulation of time-evolving qubits

Natural time-evolution of qubits is one of attractive approaches for quantum information [1]. I will talk about numerical techniques for simulating the time-evolution of interacting spins [2] and their application to quantum magnets [3] and quantum dots [4].

[1] K. Maruyama, T. Iitaka, F. Nori, Enhancement of entanglement transfer in a spin chain by phase-shift control Phys. Rev. A 75, 012325 (2007). [2] T. Iitaka, T. Ebisuzaki, Algorithm for linear response functions at finite temperatures, Application to ESR spectrum of s=1/2 antiferromagnet Cu benzoate. Phys. Rev. Lett. 90, 047203 (2003). [3] M. Machida, T. Iitaka and S. Miyashita, Temperature dependence of ESR intensity for the nanoscale molecular magnet V15, J. Phys. Soc. Jpn. Suppl. 74, 107-110 (2005). [4] Shintaro Nomura and Toshiaki Iitaka, Linear scaling calculation of a n-type GaAs quantum dot, Phys. Rev. E 76, 037701 (2007).

 

 

Wed. Oct 15

10:00 am LISE 3rd floor Room 320

Speaker: Robert Johansson: Single-artificial-atom lasing and its suppression by strong pumping

Abstract: We consider a system composed of a single artificial atom coupled to a cavity mode. The artificial atom is biased such that the most dominant relaxation process in the system takes the atom from its ground state to its excited state, thus ensuring population inversion. Even under this condition, lasing action can be suppressed if the `relaxation' rate, i.e. the pumping rate, is larger than a certain threshold value. Using simple transition-rate arguments and a semiclassical calculation, we derive analytic expressions for the lasing suppression condition and the state of the cavity in both the lasing and suppressed-lasing regimes. The results of numerical calculations agree very well with the analytically derived results. Our analysis and results are relevant to the recently realized superconducting artificial-atom laser

Reference: S. Ashhab, J.R. Johansson, A.M. Zagoskin, F. Nori Single-artificial-atom lasing and its suppression by strong pumping (2008).

4:30 Jefferson Lab 356 Special ITAMP Colloquium

Speaker: Franco Nori: Designing superconducting qubit circuits that exhibit atomic-physics-like phenomena on a chip

Abstract: Superconducting (SC) circuits can behave like atoms making transitions between a few energy levels. Such circuits can test quantum mechanics at macroscopic scales and be used to conduct atomic-physics experiments on a silicon chip. This talk overviews a few of our theoretical studies on SC circuits and quantum information processing (QIP) including: SC qubits for single photon generation and for lasing; controllable couplings among qubits; how to increase the coherence time of qubits using a capacitor in parallel to one of the qubit junctions; hybrid circuits involving both charge and flux qubits; quantum tomography in SC circuits; preparation of macroscopic quantum superposition states of a cavity field via coupling to a SC qubit; generation of nonclassical photon states using a SC qubit in a microcavity; scalable qubit circuits; and information processing with SC qubits in a microwave field. Controllable couplings between qubits can be achieved either directly or indirectly. This can be done either with or without coupler circuits, as well as either with or without data-buses like EM fields in cavities (e.g., we will describe both the variable-frequency magnetic flux approach and also a generalized double-resonance approach that we introduced). It is also possible to "turn a quantum bug into a feature'' by using microscopic defects as qubits, and the macroscopic junction as a controller of it. We have also studied ways to implement "cluster states'' in SC circuits.

For a general overview of this field, see, J.Q. You and F. Nori, Physics Today 58, No. 11, 42 (2005)

Thurs. Oct 16

10:00am - 2:00pm, Jefferson 453, Harvard Physics

10:00 Alexey Akimov, "Quantum optics with nanoscale surface plasmons"

11:00 Frank Koppens, "Near-Field Electrical Detection of Guided Surface Plasmons"

12:00 Liang Jiang, "Anyonic interferometry and protected memories in atomic spin lattices"

2:00pm - 5:00pm, Classroom, CfA

Fri. Oct 17

12:00pm , Lyman 425

Toshi Iitaka, "Quantum Dynamics"

1:00 pm, Lyman 425

Frank Gaitan, "Quantum Computing and Density Functional Theory"

 

 


Participants

Dr. Sahel Ashhab
RIKEN and Univ. of Michigan

Dr. Alan Aspuru-Guzik
Harvard Chemistry

Dr. Jim Babb
ITAMP

Dr. Jonas Bylander
MIT

Dr. Federico Capasso
Harvard Applied Sciences

Dr. Paola Cappellaro
ITAMP

Dr. Frank Gaitan
Riken and S. Illinois University

Dr. Rick Heller
Harvard Chemistry

 

Dr. Xuedong Hu
Univ. of Buffalo and RIKEN

Dr. Robert Johansson
RIKEN

Dr. Toshiaki Iitaka
RIKEN

Dr. Charles Marcus
Harvard Physics and Applied Science

Dr. Franco Nori
RIKEN and Univ. of Michigan

Dr. William Oliver
MIT

Dr. Hossein Sadgepour
ITAMP

 

Dr. T. Takada

RIKEN

Dr. J.Q. You
RIKEN and Fudan Univ.