Today is World Quantum Day. It is celebrated on April 14, a reference to 4.14, the rounded first digits of Planck’s constant which describes the behavior of particles and waves on the atomic scale, including the particle aspect of light.

World Quantum Day is a bottom-up initiative of a worldwide network of scientists, engineers, educators, communicators, entrepreneurs, technologists, and their institutions. Its primary goal is to promote public understanding of what could be the next big thing in scientific research and its applications.

Just like other next big things, the promise of quantum computing, communications, and sensing, generates venture capital funds, government involvement, large companies’ R&D investments, and many startups. Here’s a brief overview of where it’s going, where it is today, and how we got here.

**The Future of All Things Quantum **

Five developers of quantum systems have announced plans to have fault-tolerant quantum computing hardware by 2030 and many industry observers anticipate that we will see a clear quantum advantage for a number of applications such as drug discovery by then.

To get a sense of where quantum will be in the near future, I conducted over the last few days a survey of a number of experts, asking for their predictions regarding the most important quantum-related advance over the next five years. Here are the results:

Dr. Celia Merzbacher, Executive Director, The Quantum Economic Development Consortium (QED-C): “There are many areas in which advances will be needed and made related to quantum computing. One that I believe will be particularly significant is in quantum error correction, which is essential in order to achieve the full potential of quantum computing.”

Doug Finke, Managing Editor, Quantum Computing Report: “The next five years of quantum computing will be the era of the NISQ [Noisy Intermediate-Scale Quantum] machine and we will see increasingly powerful NISQ machines being introduced. Although there might be a few applications that will use these to achieve a quantum advantage, most potential quantum applications still won’t find these NISQ machines powerful enough to outperform classical computing-based solutions. However, by the end of the five-year period we will start seeing the emergence of error-corrected fault-tolerant quantum processors and this will be the inflexion point for large-scale quantum computing adoption in real world applications.”

David Awschalom, Liew Family Professor in Molecular Engineering and Physics at the University of Chicago, senior scientist at Argonne National Laboratory, director of the Chicago Quantum Exchange, and director of Q-NEXT, a Department of Energy Quantum Information Science Center: “In the Next five years, we anticipate the emergence of metropolitan-scale entangled quantum networks for secure communication. These networks may also be used to create small clusters of quantum machines for advanced computing. We also believe that quantum sensors will be employed to significantly improve clocks, mapping, and intracellular sensing.”

Itamar Sivan, co-founder and CEO, Quantum Machines: “I believe the most important advancement in quantum computing in the next five years will be the availability of quantum accelerators that can be used as seamlessly as GPUs are today. The increase in availability will lower the bar for accessibility, taking quantum computing from niche to mainstream, and enabling applications to easily benefit from quantum technologies, including improving financial modeling, significantly enhancing computational chemistry and more.”

Nir Minerbi, co-founder and CEO, Classiq Technologies: “The most important advance in quantum computing by 2027 is probably beyond our imagination. Back in the 70s, if you asked someone what could be done with billions of transistors on a chip, the answer would probably be ‘a powerful calculator’, and not ‘using a Google search’ or ‘the Internet in your pocket’. While the most important result of the quantum paradigm shift in computing is still unknown or perhaps not even invented, if we are able to ensure that quantum software progresses hand-in-hand with hardware, then by 2027 we’ll have an incredibly-powerful quantum computers that would revolutionize material science, carbon capture, supply chain optimization, and therapeutic discovery. This is one reason why I am so excited to be part of this industry today.”

**The State of Quantum Today**

The funding for quantum-related research comes largely from the public sector. China announced plans to invest $15 billion in quantum computing, the European Union $7.2 billion, the US $1.3 billion, the UK $1.2 billion, and India and Japan $1 billion each.

The private sector is engaged. Investments in quantum computing startups have surpassed $1.7 billion in 2021, more than double the amount raised in 2020, according to McKinsey. The number of software-only startups is increasing faster than any other segment of the quantum computing market.

A recent survey of business executives by Capgemini found that 23% are working with quantum technologies or planning to do so. One in ten expect quantum computing to be available for use in at least one major application within three years. 28% of companies surveyed by quantum software startup Zapata reported they have assigned a budget of $1 million or more for quantum investments. 69% of the companies surveyed say they have adopted or are planning to adopt quantum computing in the next year. Quantum-adopting enterprises are preparing on multiple fronts: 51% are identifying talent/building an internal team; 49% are experimenting and building proofs of concept; 48% are running experiments on quantum hardware or simulators; and 46% are building new applications.

**Milestones of Quantum Mechanics**

41 years ago, Nobel Prize-winner Richard Feynman argued that “nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical,” a statement later perceived as a rallying cry for developing a quantum computer. Here are (somewhat random) major milestones in the history of quantum mechanics.

1900 German theoretical physicist Max Planck suggests that radiation energy is emitted, not continuously, but rather in discrete packets called quanta.

1905 Albert Einstein extends Planck’s hypothesis to explains the photoelectric effect—shining light on certain materials can function to release electrons from the material—and suggests that light itself consists of individual quantum particles or photons.

1924 The term quantum mechanics is first used in a paper by Max Born.

1925 Werner Heisenberg, Max Born, and Pascual Jordan formulate matrix mechanics, the first conceptually autonomous and logically consistent formulation of quantum mechanics.

1930 Paul Dirac publications *The Principles of Quantum Mechanics*a textbook that has become a standard reference book that is still used today.

1935 Albert Einstein, Boris Podolsky, and Nathan Rosen publish a paper highlighting the counterintuitive nature of quantum superpositions and arguing that the description of physical reality provided by quantum mechanics is incomplete.

1935 Erwin Schrödinger, discussing quantum superposition with Albert Einstein, develops a thought experiment in which a cat (forever known as Schrödinger’s cat) is simultaneously dead and alive; Schrödinger also coins the term “quantum entanglement.”

1947 Albert Einstein refers for the first time to quantum entanglement as “spooky action at a distance” in a letter to Max Born.

1951 Felix Bloch and Edward Mills Purcell receive a shared Nobel Prize in Physics for their first observations of the quantum phenomenon of nuclear magnetic resonance.

1963 Eugene P. Wigner lays the foundation for the theory of symmetries in quantum mechanics as well as for basic research into the structure of the atomic nucleus.

1976 Roman Stanisław Ingarden publishes one of the first attempts at creating a quantum information theory.

1980 Paul Benioff publishes a paper describing a quantum mechanical model of a Turing machine or a classical computer, the first to demonstrate the possibility of quantum computing.

1985 David Deutsch of the University of Oxford formulates a description for a quantum Turing machine.

1993 The first paper^{ }describing the idea of quantum teleportation is published.

1994 Peter Shor develops a quantum algorithm for factoring integers that has the potential to decrypt RSA-encrypted communications, a widely-used method for securing data transmissions.

1996 Lov Grover invents the quantum database search algorithm.

1998 First demonstration of quantum error correction; first proof that a certain subclass of quantum computations can be efficiencies emulated with classical computers.

2004 First five-photon entanglement demonstrated by Jian-Wei Pan’s group at the University of Science and Technology in China.

2014 Physicists at the Delft University of Technology, The Netherlands, teleport information between two quantum bits separated by about 10 feet with zero percent error rate.

2017 Chinese researchers report the first quantum teleportation of independent single-photon qubits from a ground observatory to a low Earth orbit satellite with a distance of up to 1400 km.

2021 University of Chicago researchers send, for the first time, entangled qubit states through a communication cable linking one quantum network node to a second node.

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