A brief history of Quantum computers 👇 1905: Albert Einstein explains the photoelectric effect and suggests that light consists of quantum particles or photons 1924: Max Born uses the term quantum mechanics for the first time 1925: Werner Heisenberg, Max Born, and Pascual Jordan formulate matrix mechanics, the first formulation of quantum mechanics 1925-1927: Niels Bohr and Werner Heisenberg develop the Copenhagen interpretation, one of the earliest and most common interpretations of quantum mechanics 1930: Paul Dirac publishes The Principles of Quantum Mechanics, a standard textbook on quantum theory 1935: Albert Einstein, Boris Podolsky, and Nathan Rosen publish a paper highlighting the counterintuitive nature of quantum superposition and arguing that quantum mechanics is incomplete 1935: Erwin Schrödinger develops a thought experiment involving a cat that is simultaneously dead and alive, and coins the term “quantum entanglement” 1944: John von Neumann publishes Mathematical Foundations of Quantum Mechanics, a rigorous mathematical framework for quantum theory 1957: Hugh Everett proposes the many-worlds interpretation of quantum mechanics, which suggests that every possible outcome of a quantum measurement actually occurs in a parallel universe 1961: Rolf Landauer shows that erasing a bit of information dissipates a minimum amount of energy, known as Landauer’s principle 1965: John Bell proves that quantum entanglement cannot be explained by any local hidden variable theory, known as Bell’s theorem 1973: Alexander Holevo proves that n qubits cannot carry more than n classical bits of information, known as Holevo’s theorem or Holevo’s bound 1980: Paul Benioff proposes a model of a quantum Turing machine, a theoretical device that can perform any computation using quantum mechanical principles 1981: Richard Feynman suggests that simulating quantum systems would require a new type of computer based on quantum mechanics 1982: David Deutsch generalizes Benioff’s model and proposes the concept of a universal quantum computer 1984: Charles Bennett and Gilles Brassard develop a protocol for quantum key distribution, which allows two parties to securely exchange cryptographic keys using quantum states 1985: David Deutsch and Richard Jozsa devise an algorithm that can solve a specific problem faster than any classical algorithm, known as the Deutsch-Jozsa algorithm 1991: Artur Ekert proposes another protocol for quantum key distribution based on quantum entanglement, known as the E91 protocol 1992: David Deutsch and Richard Jozsa extend their algorithm to handle multiple inputs, known as the Deutsch-Jozsa algorithm 1994: Peter Shor discovers an algorithm that can factor large numbers in polynomial time using a quantum computer, known as Shor’s algorithm 1996: Lov Grover invents an algorithm that can search an unsorted database in square root time using a quantum computer, known as Grover’s algorithm 1997: Isaac Chuang, Neil Gershenfeld, and Mark Kubinec demonstrate the first implementation of Shor’s algorithm using nuclear magnetic resonance (NMR) techniques 2000: David DiVincenzo proposes five criteria for building a practical quantum computer, known as the DiVincenzo criteria 2001: IBM researchers implement Grover’s algorithm using NMR techniques and achieve a modest speedup over classical algorithms 2007: D-Wave Systems claims to have built the first commercial quantum computer, but its validity is disputed by many experts 2019: Google announces that it has achieved quantum supremacy by performing a calculation on a 53-qubit quantum processor that would take a classical supercomputer thousands of years to complete 2020: IBM demonstrates that its 65-qubit quantum processor can perform calculations beyond the reach of any classical computer 📷 An IBM QC photographed by James Estrin