Within the last two decades, quantum technologies have made significant progress, moving from Nobel Prize award-winning experiments on quantum physics (2022: Alain Aspect, John F. Clauser and Anton Zeilinger; 2012: Haroche, Wineland; 2005: Hall, Hänsch, Glauber; 2001: Cornell, Ketterle, Wieman 1997: Chu, Cohen-Tanoudji, Phillips) into a cross-disciplinary field of applied research. Technologies are being developed now that address individual quantum states and make use of quantum properties, such as entanglement and superposition. The field comprises four domains: quantum computation, communication, simulation, and sensing.
The main reason we’re discussing quantum technologies now, 50 years after they became a part of our lives through nuclear power, is that the latest achievements of engineering are utilizing more of the potential of quantum mechanics. We’re now starting to control quantum superposition and entanglement. That means quantum technology guarantees improvements to a wide range of everyday gadgets, including:
- More reliable navigation and timing systems
- More secure communications
- More accurate healthcare imaging through quantum sensing
- More powerful computing
All these implementations could, to some extent, be useful within a few years. But it’s tough to know which will be a straightforward evolution and which will be truly disruptive.
Quantum technology is a division of technology that works by using the principles of quantum mechanics (the physics of sub-atomic particles), including quantum superposition and quantum entanglement.
Quantum Superposition: Information Processing (Computing with qubits)
Quantum information processing aims at computing based on quantum mechanics. The current existing digital computers encode data in binary digits (bits – 0 and 1), quantum computers are not limited to two states. They encode information as qubits, or quantum bits, which can exist in superposition [1]. Qubits can be implemented with photons, ions, atoms, or electrons and suitable control devices that work together to act as a processor and computer memory. Because a quantum computer can contain these multiple states at the same time, they provide built-in parallelism. Figure 1 illustrates the concept of superposition of Qubits. This will allow us to solve certain problems much faster than any traditional computer using the best currently known algorithms, like integer factorization or the simulation of quantum many-body systems.
Figure 1: Qubits can be in a superposition in all the classically allowed states
Quantum Entanglement: Quantum mechanical state of separated systems
Quantum entanglement is a physical phenomenon that takes place when quantum systems such as electrons, photons, molecules, or atoms interact and then become separated so that they later share a common quantum mechanical state. Even when a pair of entangled particles are far away from each other, they remain “connected” in the perception that a computation on one of them instantly reveals the corresponding feature of the quantum state of its twin partner. These “aspects” of the quantum state can be momentum, position, polarization, spin, etc. While it can only be explained as a superposition with an indefinite value for the entangled pair, the computation on one of the partners produces a definite value that instantly also determines the corresponding value of the other. Figure 2 illustrates the concept of an entangled pair of atoms. The astonishing “remote connection” between the partners and their instant actions like faster than light that would seem to deny relativity has been the motive for enormous research efforts, both experimentally and theoretically [2].
Figure 2: Concept of entangled pair
Now, let’s go through the current and future implementations of each quantum technology field in detail.
Quantum computing:
Quantum computing is completely different from today’s predominant digital computers. The quantum computers become powerful from the fact that they’re not limited to binary bits (the zeros and ones of traditional computer processors). Instead, they use qubits or quantum bits that can represent a zero, a one, or both at once – a ‘superposition state’ that encompasses a near-infinite scope of probabilities.
Quantum computers deal with problems very differently by processing them concurrently rather than sequentially. They handle the properties of quantum entangled qubits to concurrently try a vast number of solutions, rather than trying each in turn. This leads to dramatic increases in speed when solving certain groups of problems. For example, geophysical analysis in oil and gas exploration, pharmaceutical drug discovery, chemical and materials science, and weather and financial forecasting. In these fields, some organizations are already investing in quantum capabilities, such as Renaissance and DE Shaw [3] and Biogen [4].
As the first generation of quantum computing progresses over the next decade, a wider range of organizations will have the chance to approach quantum-as-a-service potentialities via the cloud and standardized and specialized quantum algorithms. But for first movers, there are the right set of circumstances to seize today.
Quantum Sensing:
Quantum sensing covers motion – including rotation, acceleration, and gravity; magnetic and electric fields; and imaging. With such fundamental measurements, there are many possible application areas, including transport and aerospace, medicine, and civil engineering. Many of the distinct quantum technologies can be used in various areas. For instance, cold atom technologies, which usually use superposition, are used for sensing applications.
Cold atom technologies [5] include cooling atoms in a vacuum chamber to a few microkelvins above absolute zero. In this state, the atoms are responsive to motion, particularly rotation and acceleration (gravity). Gravity sensors built on this can provide a view underground on roads and brownfield building sites, allowing faster survey times with decreased operational running costs.
Quantum principles are also used in magnetic field sensing. Both nitrogen-vacancy (NV) in diamond and cold atom technologies have been used for this purpose. NV covers the way to decrease the size, weight, power, and cost (SWaP-C) of MRIs compared with similar scanning technologies. The future for quantum sensing is promising as one of the benefits of quantum sensing is the enhancement in sensitivity over classical systems.
Quantum Communication:
Quantum communication is a field of applied quantum physics closely connected to quantum teleportation and quantum information processing. Its most absorbing application is safeguarding information channels against eavesdropping by means of quantum cryptography. The most developed and well-known application of quantum cryptography is quantum key distribution (QKD). QKD explains the use of quantum mechanical results to perform cryptographic tasks or to break cryptographic systems.
The principle of operation of a QKD system is quite straightforward: two systems (sender and receiver) use single photons that are arbitrarily polarized to states that stand for zeros and ones to transmit a series of random number patterns that are used as keys in cryptographic communications. Both stations are linked together with a public channel and a quantum channel. Sender generates a random stream of qubits that are sent over the quantum channel. Upon reception of the stream, the Receiver and Sender using the public channel perform classical operations to examine if an eavesdropper has tried to take out information on the qubits stream. The presence of an eavesdropper is disclosed by the imperfect correlation between the two lists of bits acquired after the transmission of qubits between the sender and the receiver. Figure 3 illustrates the concept of QKD communication. One important thing for all proper encryption schemes is true randomness which can elegantly be generated by means of quantum optics.
Figure 3: QKD communication between the systems
Secure solutions based on quantum encryption by quantum computers (QCs) are important and also immune to attacks and are commercially available today, as is quantum random number generation (QRNG). In fact, recently it has been shown that the camera in mobile phones can be used as a QRNG [6], opening the door to enormous commercial opportunities.
Currently, classical fiber-based QKD systems can only operate over distances of around 100 km for commercial systems, even though academic prototypes can push this to around 300 km [7], which is restricted by transmission loss in optical fibers; quantum information is secure because it cannot be cloned, but for the same reason, it cannot be relayed through traditional repeaters. In the coming years, we will likely see QKD demonstrating long distances via trusted-nodes, test-bed networks, HAPS, or satellites, as well as switchable or multi-node intra-city networks, all of the applications will require large-scale infrastructure projects to be initiated.
Conclusion:
In this paper, the fundamental principles used in the quantum technologies and three well-known quantum applications (computing, sensing, and communication) were introduced. Quantum computing is a promising technology, which changes our lives in many ways. Quantum computer upgrades database search significantly and cracks many optimization problems used in business such as data analytics, logistics, and medical research. Although it may take a few more years to build a quantum computer that significantly surpasses classical computers, every business requires thinking of new quantum applications to prepare for the day. Currently, Fortune 500 companies have invested in quantum computing, there must be the possibility to find a high rate of opportunities in this research and business fields.
References:
1. An introduction to quantum computing: Yason S. Yanofsky:
https://www.researchgate.net/publication/1758552_An_Introduction_to_Quantum_Computing
2. Multiplexed entangled photon sources for all fiber quantum networks: Li Y.-H., Zhou Z.-Y., Xu Z.-H., Xu L.-X., Shi B.-S., Guo G.-C.
Physical Review A, Vol.094, 043810 (2016)
https://arxiv.org/ftp/arxiv/papers/1605/1605.04701.pdf
3. Financial Times: Renaissance, DE Shaw look to quantum computing for edge
https://www.ft.com/content/60fded2a-be5a-11e7-b8a3-38a6e068f464
4. PMLive: Biogen develops quantum computing-based app to speed drug discovery
5. Cold atoms for Quantum Technology
https://www5.open.ac.uk/science/physical-science/research/physics/cold-atoms-quantum-technology
6. Quantum random number generation on a mobile phone:
Bruno Sanguinetti,Anthony Martin, Hugo Zbinden and Nicolas Gisin
Group of Applied Physics, University of Geneva, Switzerland
https://arxiv.org/abs/1405.0435
7. Provably Secure and Practical Quantum Key Distribution over 307 km of Optical Fibre:
Boris Korzh, Charles Ci Wen Lim, Raphael Houlmann, Nicolas Gisin, Ming Jun Li, Daniel Nolan, Bruno Sanguinetti, Rob Thew, Hugo Zbinden