Schrödinger’s Web

Jonathan Dowling earned a Ph.D. in Mathematical Physics from theUniversity of Colorado. He has worked at the United States ArmyAviation and Missile Command, the NASA Jet Propulsion Laboratory,and then at the Louisiana State University. Dr. Dowling is one of thefounders of the U.S. Government program in quantum computing andquantum cryptography.

• ContentsPreface, xiiiForeword, xvAuthor, xxiCHAPTER 1 ■ Many Hands Make Light Work 1THE DARKENED ROOM 2NEWTON’S BULLETS 5WAVES OF HUYGENS’ – PTOOEY! 11OUT – DAMNED SPOT! 12THE JOURNEY STONE 20FRANKLIN, FROGS, AND FRANKENSTEIN 22ØRSTED UNLODES 23ELECTRIC BOY REWINDS 26ALL’S WELL THAT’S MAXWELL 31FIAT LUX! 34WATT IS LOVE? DON’T HERTZ ME, NO MORSE! 38MARCONI AND CHUTZPAH 39MAXWELL’S RAINBOW 40CHAPTER 2 ■ What Light Through Yonder Window –Breaks? 43THE END OF PHYSICS? 44PLANCKING FOR BEGINNERS 51ONE PHOTON, INDIVISIBLE, WITH QUANTA OFENERGY, IN BALLS 56IT’S A WAVE! IT’S A PARTICLE! IT’S – WHAT THE HECKIS IT!? 60QUANTUM NONDEMOLITION DERBY 68VAIDMAN – DUDE’S THE BOMB! 73THE UNDETECTABLE QUANTUM TRIPWIRE 76EXTRAORDINARY POPULAR DELUSIONS AND THEMADNESS OF CLOUDS 79TO COMPUTE OR NOT TO COMPUTE – WHAT ISTHE QUESTION? 82EINSTEIN’S BUBBLE – TOIL AND TROUBLE 83PARTICULARS OF POLARIZED PHOTONS 87CHAPTER 3 ■ It Takes Two to Tangle 91SCHRÖDINGER’S CURSE 92EINSTEIN’S BANE 94VON NEUMANN’S BLUNDER 99BOHM’S BOMBSHELL 101BELL GETS TESTY 103BERTLMANN’S SOCKS 108CLAUSER’S NO-BELL PRIZE 108CLOSING THE LOOPHOLES 112TWO’S COMPANY – BUT THREE’S A CLOUD 115SPEAKING THE UNSPEAKABLE 118CHAPTER 4 ■ Quantum Networks: The Building Blocks 121SINGLE-PHOTON GUNS 122QUANTUM-DOT SINGLE-PHOTON GUNS 122SORT-OF-SINGLE-PHOTON GUNS AND MAGIC CHINESECRYSTALS 125PSEUDO-SINGLE-PHOTON GUNS 129ENTANGLED-PHOTON GUNS 132QUANTUM-DOT ENTANGLED-PHOTON GUNS 132ENTANGLED SORT-OF-PHOTON GUNS AND MAGICCHINESE CRYSTALS 134I SPY, WITH MY LITTLE EYE 138E. T. PHONE HOME 141POLARIZE! LET NO PHOTON EVADE YOUR EYES! 146RARE AS A TWO-DOLLAR BELL 149CHAPTER 5 ■ The Second Quantum Revolution 151WHAT IS QUANTUM TECHNOLOGY? 152QUANTUM RANDOM-NUMBER GENERATORS 154CRYPTOGRAPHY 158CLASSICAL CRYPTOGRAPHY – RSA PUBLIC-KEYENCRYPTION 159CLASSICAL CRYPTOGRAPHY – ONE-TIME-PADPRIVATE-KEY ENCRYPTION 162QUANTUM MONEY – WIESNER’S UNPUBLISHABLEPAPER 172QUANTUM CRYPTOGRAPHY – THE BENNETT ANDBRASSARD 1984 PROTOCOL 175QUANTUM CRYPTOGRAPHY – THE EKERT 1991PROTOCOL 182POST-QUANTUM-CRYPTOGRAPHY – OFF-RAMPON THE QUANTUM INTERNET 185QUANTUM TELEPORTATION 187ENTANGLEMENT SWAPPING 194QUANTUM MEMORIES 196CLASSICAL REPEATERS 198QUANTUM REPEATERS 201QUANTUM TRANSPONDERS 205CHAPTER 6 ■ Quantum Networks 207THE QUANTUM INTERNET – WHY NOW? 208WHAT’S UP WITH QUANTUM COMPUTERSTHESE DAYS? 210QUANTUM SUPREMACY 213DOUBLE-BUBBLE – TOIL AND TROUBLE! 215A CHINESE QUANTUM-SPUTNIK MOMENT 219NATIONAL QUANTUM INITIATIVE ACT 222QUANTUM INTERNET 1.0 – ALL THAT IT’S CRACKEDUP TO BE? 228QUANTUM INTERNET 2.0 – RAGE OF ENTANGLEMENT 230QUANTUM INTERNET 3.0 – RISE OF THE UBIQUITOUSQUANTUM REPEATERS 238I HAVE A CODE IN MY NODE! 245TELEPORTATION AND DISTRIBUTED QUANTUMCOMPUTING 247CLASSICAL COMMUNICATION OVER THE QUANTUMNETWORK 251CHAPTER 7 ■ Networks of Quantum Sensors 255QUANTUM SENSORS 256COHERENT SENSOR ARRAYS 261CLOCKS IN SPACE 270DISTRIBUTED QUANTUM SENSORS 273EPILOGUE, 281INDEX, 285

"As theoretical physicist Jonathan Dowling makes clear in Schrödinger’s Web, early versions of the quantum internet are here already — for example, quantum communication has been taking place between Beijing and Shanghai via fiber-optic cables since 2016 — and more are coming fast. So now is the perfect time to read up. Dowling, who helped found the U.S. government’s quantum computing program in the 1990s, is the perfect guide. Armed with a seemingly endless supply of outrageous anecdotes, memorable analogies, puns and quips, he makes the thorny theoretical details of the quantum internet both entertaining and accessible. …Like Dowling’s 2013 book on quantum computers, Schrödinger’s Killer App, Schrödinger’s Web hammers home the nonintuitive truths at the heart of quantum mechanics. … Dowling died unexpectedly in June at age 65, before he could see this future come to fruition. Once when I interviewed him, he invoked Arthur C. Clarke’s first law to justify why he thought another esteemed scientist was wrong. "The first law is that if a distinguished, elderly scientist tells you something is possible, he’s very likely right," he said. "If he tells you something is impossible, he’s very likely wrong." Dowling died too soon to be considered elderly, but he was distinguished, and Schrödinger’s Web lays out a powerful case for the possibility of a quantum internet."—Dan Garisto in Science News, September 2020