Quantum physics what everyone needs to know 1st edition by Michael Raymer ISBN 0190250720‎ 978-0190250720

Acknowledgments

A Note for Experts about Language

1. Quantum Physics

What is quantum physics?

How does quantum physics affect everyday life?

What is a physics theory and what is the program of physics?

Why do we use the word ‘model’ when referring to physics?

Why was 2015 an especially good year for quantum physics?

Why are some objects well described by classical physics models whereas others require a quantum physics description?

What are the elementary entities that make up the physical universe?

How is light different in classical and quantum descriptions?

What are consequences of the discreteness of light detection?

Is it possible to create and detect exactly one photon?

How was quantum physics discovered?

Do electromagnetic fields have a quantum nature?

Notes

2. Quantum Measurement and Its Consequences

What is measurement in classical physics?

What is light polarization?

How do we determine or measure light polarization?

What happens if the light contains a mixture of polarizations?

What happens if the light is purely polarized other than H or V?

What is the physics behind these polarization measurement results?

What is coherence and what role does it play?

Can we measure the polarization of a single photon?

How can we prepare a photon with a particular pure polarization?

Can you determine the polarization of a single photon by quantum measurement?

What is the difference between the classical and quantum concepts of polarization of light?

How do we predict probabilities for photon polarization measurements?

What does it mean to make a measurement in the quantum realm?

What is measurement complementarity?

How can a human-scale object seem to possess definite properties if the individual quantum objects making it up do not?

What do we mean by the state of an object?

What is a quantum state?

Can Bob determine a quantum state experimentally that was prepared by Alice?

Can Bob make copies (clones) of the state of a single photon?

What is quantum coherence?

What are the Guiding Principles of quantum mechanics?

What does quantum mechanics really describe?

Notes

3. Application: Quantum Data Encryption

Can quantum physics be harnessed to create perfectly secure Internet communication?

How does encryption keep messages secret?

Can most encryption methods typically be cracked?

Is there an encryption method that cannot be cracked?

How is text represented using binary symbols?

How is a text message encrypted and decrypted using a binary key?

How can photon polarization be used for creating secure encryption keys?

What physics principles underlie quantum key distribution?

How does quantum key distribution work?

What if an eavesdropper is present?

How can Alice and Bob detect Eve’s presence?

What if Eve is always present?

Could Eve devise other, better eavesdropping schemes?

What is the current status of quantum key distribution?

Further Reading

4. Quantum Behavior and Its Description

How do quantum objects behave in the absence of measurement?

How do electrons and pinballs behave differently?

Why does the electron always go toward the goat?

What happens if we modify the setup?

What if we block one path?

What can we conclude so far?

Can we measure which way the electron travels?

Why can’t we apply this same reasoning to the pinball?

What is unitary behavior?

What other examples of unitary processes illustrate the main points?

What are additional consequences of a process being unitary?

Can matter behave the same as photons in the two-path experiment?

Can a photon sometimes behave according to classical probability?

How can we summarize the previous considerations as a principle of physics?

What is a measurement in quantum physics?

Can a quantum object exist in two places at once?

How does quantum key distribution make use of unitary processes?

How does quantum theory describe states in which two possibilities exist?

How does quantum theory describe an electron having two possible paths?

Can arrows be used to represent the state of macroscopic objects?

How are outcome probabilities related to possibilities?

How can an electron be split into two possible paths?

How are state arrows used to find probabilities when path interference occurs?

What happens if we alter one of the paths?

How can we summarize the previous ideas in a Guiding Principle?

What if we change the path length even more?

Is there a general principle we can infer from this experiment?

What are the take-away messages from this chapter?

Notes

5. Application: Sensing Gravity with Quantum Interference

What is the technology of sensing?

Why is sensing the strength of gravity useful?

How can quantum physics be used to sense gravity?

How is this interferometer different from the one discussed in the previous chapter?

Is this apparatus a practical gravity sensor?

Figure Notes

6. Quantum Possibilities and Waves

How does the concept of waves enter quantum theory?

What are waves?

What is wave interference?

What are quantum possibility waves?

How does a psi wave keep track of its internal timing?

What sets the cycle time or ticking rate of a particle’s internal clock?

How can we assemble our Guiding Principles into a coherent quantum theory?

What is momentum and what can change it?

What is energy?

How does Schrödinger’s equation describe quantum objects moving through space?

How is the quantum wave related to probability?

What is an example of Schrödinger’s equation in action?

How does a quantum particle get through locations of zero probability?

What is Heisenberg’s Uncertainty Principle?

Is it correct to say an electron is both a particle and a wave?

Notes

7. Milestones and a Fork in the Road

What aspects of quantum physics have we seen so far, and what topics should we discuss next?

What milestones have we passed so far?

Note

8. Bell-Tests and the End of Local Realism

Can experiments probe the nature of reality?

What is correlation and what does it tell us?

What is an example of correlated properties?

What is an example of correlated behaviors?

How can correlations be quantified?

What is the difference between classical correlation and quantum correlation?

What is realism and how can we test it experimentally?

Setting the stage for experimental tests of realism

What if we can make only partial measurements?

What prevents communication between the two sides of the experiment?

What is Local Realism?

What kinds of experiments can put an end to Local Realism?

Would all states of light emitted by the atoms produce this same result?

Are there possible flaws or loopholes in our arguments?

What experiments have overcome the potential flaws?

How can we be sure the measurement settings are independent?

What did John Bell make of the results of such experiments?

Does the breakdown of Local Realism mean we must abandon classical intuition and classical physics altogether?

Should we abandon Local Causality or Local Realism, or both?

Figure Notes

Notes

9. Quantum Entanglement and Teleportation

What is quantum entanglement?

How do we represent the state of a composite entity?

How do we represent an entangled state of a pair of photons?

How can we make the Bell State for a photon pair?

How does the entangled Bell State violate Local Realism?

What can you know about the constituents of a quantum composite object?

What does it mean in practice to know everything there is to know about a composite quantum entity?

What can we accomplish using entanglement that we couldn’t without it?

How does entanglement enable quantum state teleportation?

Does what happens on Alice’s side affect what happens on Bob’s side?

Is quantum teleportation instantaneous?

Can a human be teleported?

What is quantum state teleportation good for?

Notes

10. Application: Quantum Computing

Is information physical?

What is a computer?

How do computers work?

How small can a single logic gate be?

Can we create computers that use intrinsically quantum behavior?

What is a qubit?

What physical principles set classical and quantum computers apart?

What logic gates would quantum computers use?

How would quantum computers operate?

Why is factoring numbers difficult?

How could quantum computers solve the factoring problem?

What other computer science problems could quantum computers solve?

Which physics and chemistry problems could quantum computers solve?

Why are quantum computers so hard to make?

What are the prospects for building quantum computers?

What are the promising approaches to building quantum computers?

Notes

Further Reading

11. Energy Quantization and Atoms

What is energy quantization in quantum mechanics?

Why is energy quantized when a particle is confined?

How is the energy of an electron in an atom quantized?

Why can’t the electron come to rest at the bottom of the valley?

How does an atom absorb light?

How does an atom emit light?

What has become of the classical physics idea that an electron in an atom orbits around the nucleus?

What do electron psi waves look like in three dimensions?

Note

12. Application: Sensing Time, Motion, and Gravity with Quantum Technology

What are quantum physics–based sensing technologies?

What is a scientific definition of time?

What is a clock?

How can we make clocks identical?

Why do elementary quantum objects make the most perfect clocks?

Why are good clocks technologically important?

How precise are today’s atomic clocks?

How do basic atomic clocks work?

How do the most advanced atomic clocks work?

What are inertial sensors?

What is an accelerometer?

How do conventional accelerometers work?

What are accelerometers good for?

What are gravimeters and what are they used for?

How do conventional gravimeters work?

How does a basic quantum gravimeter work?

How do advanced quantum gravimeters work?

Can atomic interferometers detect gravitational waves?

Figure Note

Notes

13. Quantum Fields and Their Excitations

What are classical particles and fields?

What quantum physics principle unifies the concepts of particles and fields?

What happens if we measure a quantum field?

How does the quantum theory of a grid apply to light?

What is a quantum field?

What is a photon?

Are particles and fields aspects of the same thing?

Does the unification of fields and particles also apply to electrons?

Why don’t we see ordinary objects appearing and disappearing?

What is the universe made of?

What is the quantum vacuum?

How did the elementary particles get their mass?

What other facts speak in favor of the existence of quantum fields?

Does an understanding of quantum fields remove the mystery of Bell correlations?

Does an understanding of quantum fields remove the mystery of quantum measurement?

Why is the discussion of quantum fields postponed to near the end of this book?

Notes

14. Future Directions and Remaining Questions in Quantum Science

What is needed to make further progress?

What don’t we know about quantum technology?

What don’t we know about quantum physics?

What do we understand about the quantum aspects of Nature?

How do the classical and quantum descriptions of Nature differ?

What challenges remain in understanding quantum theory?

What is the measurement problem?

How can an entangled state be updated?

Does Heisenberg’s view solve the measurement problem?

How does decoherence help?

Is decoherence sufficient?

Is quantum probability personal?

Is it all in my head?

Coherence forever?

Why do the Bell correlations occur?

Notes

Index