*J. C. Garrison and R. Y. Chiao*

- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780198508861
- eISBN:
- 9780191708640
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198508861.003.0021
- Subject:
- Physics, Atomic, Laser, and Optical Physics

This chapter addresses quantum information transmission and processing. Quantum noise is dominant in long-haul transmission lines, even for strong signals. Amplifier noise is avoided by using a ...
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This chapter addresses quantum information transmission and processing. Quantum noise is dominant in long-haul transmission lines, even for strong signals. Amplifier noise is avoided by using a noise-free amplifier. Injecting a strongly squeezed state into an unused port of a coupler reduces branching noise. The next section explains the no-cloning theorem and the theory and experimental evidence for (imperfect) quantum cloning machines. The use of single photons for secure quantum key distribution in cryptography is then discussed. Entanglement as a quantum resource first appears in the explanation of quantum dense coding and the inverse process of quantum teleportation. The chapter ends with a brief discussion of quantum computing, including quantum parallelism, quantum logic gates, and quantum circuits. A survey of experiments in quantum computing is followed by a study of proposals for combining linear optics with local measurements to construct quantum computers.Less

This chapter addresses quantum information transmission and processing. Quantum noise is dominant in long-haul transmission lines, even for strong signals. Amplifier noise is avoided by using a noise-free amplifier. Injecting a strongly squeezed state into an unused port of a coupler reduces branching noise. The next section explains the no-cloning theorem and the theory and experimental evidence for (imperfect) quantum cloning machines. The use of single photons for secure quantum key distribution in cryptography is then discussed. Entanglement as a quantum resource first appears in the explanation of quantum dense coding and the inverse process of quantum teleportation. The chapter ends with a brief discussion of quantum computing, including quantum parallelism, quantum logic gates, and quantum circuits. A survey of experiments in quantum computing is followed by a study of proposals for combining linear optics with local measurements to construct quantum computers.

*John Garrison and Raymond Chiao*

- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780198508861
- eISBN:
- 9780191708640
- Item type:
- book

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198508861.001.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics

Quantum optics is the field of physics describing the interaction of individual photons with matter, but in recent years it has expanded beyond pure physics to become an important driving force for ...
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Quantum optics is the field of physics describing the interaction of individual photons with matter, but in recent years it has expanded beyond pure physics to become an important driving force for technological innovation. This book starts with an elementary description of the underlying physics and then builds up a more advanced treatment. The theory begins with the quantum description of the simple harmonic oscillator, and is subsequently extended to provide the tools required to discuss coherent states, the interaction of light with atoms, entangled states, quantum noise and dissipation, linear optical amplifiers, and the fundamental issues associated with Bell's theorem. There is an equally strong emphasis on experimental methods. A quantum description of lenses, mirrors, beam splitters, Y-junctions, circulators, and stops is applied to a collection of important experiments in linear optics. A description of the most important methods of primary photon detection is followed by an explanation of heterodyne and homodyne techniques. Spontaneous down conversion and quantum tomography are discussed, together with important experimental applications. These experimental and theoretical considerations come together in a chapter briefly discussing quantum noise and its suppression in telecommunications; the limitations and possibilities for quantum cloning; the principles and techniques of quantum cryptography; and the physical basis for quantum computing.Less

Quantum optics is the field of physics describing the interaction of individual photons with matter, but in recent years it has expanded beyond pure physics to become an important driving force for technological innovation. This book starts with an elementary description of the underlying physics and then builds up a more advanced treatment. The theory begins with the quantum description of the simple harmonic oscillator, and is subsequently extended to provide the tools required to discuss coherent states, the interaction of light with atoms, entangled states, quantum noise and dissipation, linear optical amplifiers, and the fundamental issues associated with Bell's theorem. There is an equally strong emphasis on experimental methods. A quantum description of lenses, mirrors, beam splitters, Y-junctions, circulators, and stops is applied to a collection of important experiments in linear optics. A description of the most important methods of primary photon detection is followed by an explanation of heterodyne and homodyne techniques. Spontaneous down conversion and quantum tomography are discussed, together with important experimental applications. These experimental and theoretical considerations come together in a chapter briefly discussing quantum noise and its suppression in telecommunications; the limitations and possibilities for quantum cloning; the principles and techniques of quantum cryptography; and the physical basis for quantum computing.

*M. Suhail Zubairy*

- Published in print:
- 2020
- Published Online:
- June 2020
- ISBN:
- 9780198854227
- eISBN:
- 9780191888649
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198854227.003.0011
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology, Theoretical, Computational, and Statistical Physics

Heisenberg’s uncertainty relation and Bohr’s principle of complementarity form the foundations of quantum mechanics. If these are violated then the edifice of quantum mechanics can come crashing ...
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Heisenberg’s uncertainty relation and Bohr’s principle of complementarity form the foundations of quantum mechanics. If these are violated then the edifice of quantum mechanics can come crashing down. In this chapter, it is shown how cloning or perfect copying of a quantum state can potentially lead to a violation of these sacred principles. A no-cloning theorem is proven showing that the cloning of an arbitrary quantum state is not allowed. The foundation of quantum mechanics is therefore protected. It is also shown how quantum cloning can lead to superluminal communication. It is also discussed that, if making a perfect copy of a quantum state is forbidden, how best a copy of a state can be made.Less

Heisenberg’s uncertainty relation and Bohr’s principle of complementarity form the foundations of quantum mechanics. If these are violated then the edifice of quantum mechanics can come crashing down. In this chapter, it is shown how cloning or perfect copying of a quantum state can potentially lead to a violation of these *sacred* principles. A no-cloning theorem is proven showing that the cloning of an arbitrary quantum state is not allowed. The foundation of quantum mechanics is therefore protected. It is also shown how quantum cloning can lead to superluminal communication. It is also discussed that, if making a perfect copy of a quantum state is forbidden, how best a copy of a state can be made.