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Ebook: Experimental Quantum Computation and Information
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This Fermi Summer School of Physics on "Experimental Quantum Information and Computing" represents a primer on one of the most intriguing and rapidly expanding new areas of physics. In this part, the interest in quantum information (QI) science is due to the discovery that a computer operating on quantum mechanical principles can solve certain important computational problems exponentially faster than any conceivable classical computer. But this interest is also due to the interdisciplinary nature of the field: the rapid growth is attributable, in part, to the stimulating confluence of researchers and ideas from physics, chemistry, mathematics, information theory, and computer science. Physics plays a paramount role in QI science, as we realize that computing is itself a physical process subject to physical laws. The incredible growth of classical computers and information processors in the 20th century stems from Turing's notion that a computer is independent of the physical device actually being used; be they relays, vacuum tubes, or semiconductor transistors. As we strive to build useful quantum information processors into the 21st century, we thus look for any physical system that obeys the laws of quantum mechanics, from single photons and atoms to quantum superconducting devices. These Fermi lectures take us on a journey through these and other promising current experimental candidates for QI processing, spanning quantum optics and laser physics, atomic and molecular physics, physical chemistry, and condensed-matter physics. While this broad coverage of experimental physics represents a challenge to the student, such an appreciation of these fields will be critical in the future success of quantum technology. Indeed, the most exciting feature of QI science is that the technology ultimately leading to a quantum processor is likely presently unknown.
Quantum mechanics is heralded as the most successful and revolutionary scientific theory in the 20th century, despite its bizarre features that defy our everyday experience. This dichotomy has fascinated students of physics over the last 70 years. The recent advent of quantum information science has once again brought quantum mechanical foundations to the forefront. We are now in a position to revisit some of the fundamental principles of quantum mechanics in the laboratory, as impressive advances in experimental techniques are making yesterday's gedanken experiment today's reality.
This Fermi Summer School of Physics on “Experimental Quantum Computation and Information” represents a primer on one of the most intriguing and rapidly expanding new areas of physics. In part, the interest in quantum information (QI) science is due to the discovery that a computer operating on quantum mechanical principles can solve certain important computational problems exponentially faster than any conceivable classical computer. But this interest is also due to the interdisciplinary nature of the field: the rapid growth is attributable, in part, to the stimulating confluence of researchers and ideas from physics, chemistry, mathematics, information theory, and computer science.
Physics plays a paramount role in QI science, as we realize that computing is itself a physical process subject to physical laws. The incredible growth of classical computers and information processors in the 20th century stems from Turing's notion that a computer is independent of the physical device actually being used; be they relays, vacuum tubes, or semiconductor transistors. As we strive to build useful quantum information processors into the 21st century, we thus look for any physical system that obeys the laws of quantum mechanics, from single photons and atoms to quantum superconducting devices. These Fermi lectures take us on a journey through these and other promising current experimental candidates for QI processing, spanning quantum optics and laser physics, atomic and molecular physics, physical chemistry, and condensed-matter physics. While this broad coverage of experimental physics represents a challenge to the student, such an appreciation of these fields will be critical in the future success of quantum technology. Indeed, the most exciting feature of QI science is that the technology ultimately leading to a quantum processor is likely presently unknown.
In all, twelve lecturers, thirteen seminar speakers, and forty-nine students from eleven countries participated in the School. We benefited from an idyllic location, a cooperative atmosphere, and a friendly interchange of scientific ideas between lecturers and students. It is our hope that this event will remain in the memories of its participants for many years to come, perhaps as an educational bookmark, or even as a moment when one has learned something new while enjoying the stunning scenery of Lago di Como and the surrounding mountains.
The organization of any school, and particularly one covering so many different fields in physics, cannot be accomplished without significant and generous assistance from individuals and agencies. We are especially indebted to the Italian Physical Society President Prof. Franco Bassani for his oversight of the school, and conference administrator Barbara Alzani for her continuous effort in making the Summer School run smoothly. We are also grateful to Ramona Brigatti, Francesca Fusina, and Matteo Pozzi for their efficient organization of activities in and near Varenna.
F. De Martini and C. Monroe
1. Foreword
2. Introduction
3. The cavity QED entangling machine
4. The quantum Rabi oscillation
5. Creation of an EPR pair
6. The quantum phase gate
7. Absorption-free detection of a single photon
8. Engineered entanglement of three quantum systems
9. Non-resonant entanglement
10. Conclusions and perspectives
1. Introduction
2. A short review of cavity quantum electrodynamics
3. Three-level atoms
4. Adiabatic passage
5. Single-photon sources
6. Summary and outlook
1. Introduction
2. Basic properties of Rydberg atoms
3. Forming superposition states
4. Measuring sculpted Rydberg wave packets
5. Quantum information applications
6. Conclusion
1. Introduction
2. Conclusion
1. Introduction
2. Neutral atom qubits
3. Initialization
4. Gates
5. Coherence
6. Measurement
7. Summary
1. Introduction
2. Ions within a BEC
3. Experimental setup
4. Experimental results
5. Toward quantum gates
1. Introduction
2. Experimental setup
3. Bose-Einstein phase transition in lower dimensions
4. Expansion of a BEC from the combined trap
5. Superfluid dynamics
6. Observation of a Josephson current in an array of coupled BECs
7. Conclusions
1. Introduction
2. Trapology
3. Ion entanglement
4. Motion decoherence
5. Entanglement-enhanced quantum measurement: “spin squeezing”
6. Towards a quantum computer
7. Summary
1. Introduction
2. Scheme of an ion trap quantum computer
3. Linear ion traps
4. Ca+ for quantum computation
5. Laser cooling of trapped ions
6. Addressing of individual ions
7. Manipulation of the quantum information
8. Conclusions and outlook
1. Introduction
2. Tools
3. Bell experiments
4. QKD
5. Conclusions
1. Introduction
2. Quantum dots for quantum computing
1. Introduction
2. Basic concepts in quantum information theory
3. Quantum information processing with single atoms and photons
4. Quantum information processing with atomic ensembles
5. Summary
1. Introduction
2. Reducing errors via symmetrisation
3. Basics of classical error correction
4. Quantum error-correcting codes
5. Conclusion
1. Introduction
2. Geometric phases
3. Geometric quantum computation
4. Geometric phases in Josephson nanocircuits
1. Talbot effect, revivals and factorization
2. Model of Talbot effect
3. Mathematics of the Talbot effect
4. Particle in a box
5. Time evolution and autocorrelation function
6. Fractional revivals
7. Factorization using wavepackets
8. Gauss sums and factorization
9. Conclusions and outlook
1. Introduction
2. Definition of the problem
3. Homodyne tomography, i.e. tomography for continuous variables
4. Pauli tomography, i.e. tomography for qubits
5. Some experimental results
6. Tomography of a quantum device
7. Conclusions and future perspectives