In a new Physical Review Letters study, scientists have successfully presented a proof of concept to demonstrate a randomness-free test for quantum correlations and non-projective measurements, offering a groundbreaking alternative to traditional quantum tests that rely on random inputs.
“Quantum correlation” is a fundamental phenomenon in quantum mechanics and one that is central to quantum applications like communication, cryptography, computing, and information processing.
Bell’s inequality, or Bell’s theory, named after physicist John Stewart Bell, is the standard test used to determine the nature of correlation. However, one of the challenges with using Bell’s theorem is the requirement of seed randomness for selecting measurement settings.
The famous Copenhagen Interpretation favored by the founders of quantum mechanics is most definitely psi-epistemic. Niels Bohr, Werner Heisenberg, and others saw the state vector as being related to our interactions with the Universe. As Bohr said, “Physics is not about how the world is; it is about what we can say about the world.”
QBism is also definitively psi-epistemic, but it is not the Copenhagen Interpretation. Its epistemic focus grew organically from its founders’ work in quantum information science, which is arguably the most important development in quantum studies over the last 30 years. As physicists began thinking about quantum computers, they recognized that seeing the quantum in terms of information — an idea with strong epistemic grounding — provided new and powerful insights. By taking the information perspective seriously and asking, “Whose information?” the founders of QBism began a fundamentally new line of inquiry that, in the end, doesn’t require science fiction ideas like infinite parallel universes. That to me is one of its great strengths.
But, like all quantum interpretations, there is a price to be paid by QBism for its psi-epistemic perspective. The perfectly accessible, perfectly knowable Universe of classical physics is gone forever, no matter what interpretation you choose. We’ll dive into the price of QBism next time.
Quantum physicists have simulated super diffusion in quantum particles on a quantum computer, paving the way for deeper insights into condensed matter physics and materials science. This achievement, realized on a 27-qubit system programmed remotely from Dublin, emphasizes the potential of quantum computing in both commercial and fundamental physics inquiries.
Quantum physicists at Trinity, working alongside IBM Dublin, have successfully simulated super diffusion in a system of interacting quantum particles on a quantum computer.
This is the first step in doing highly challenging quantum transport calculations on quantum hardware and, as the hardware improves over time, such work promises to shed new light in condensed matter physics and materials science.
Physicists have performed the first quantum calculations to be carried out using individual atoms sitting on a surface.
The technique, described on 5 October in Science1, controls titanium atoms by beaming microwave signals from the tip of a scanning tunnelling microscope (STM). It is unlikely to compete any time soon with the leading approaches to quantum computing, including those adopted by Google and IBM, as well as by many start-up companies. But the tactic could be used to study quantum properties in a variety of other chemical elements or even molecules, say the researchers who developed it.
At some level, everything in nature is quantum and can, in principle, perform quantum computations. The hard part is to isolate quantum states called qubits — the quantum equivalent of the memory bits in a classical computer — from environmental disturbances, and to control them finely enough for such calculations to be achieved.
A team of astrophysicists says they may have found evidence for “cosmic strings”, long-hypothesized defects in the universe left over from its early in its expansion.
Cosmic strings were first suggested in the 1970s by theoretical physicist Tom W. B. Kibble, and later revived in the context of string theory. The one-dimensional strings, far narrower even than a proton, are thought to have sprung into existence in the very first second of the universe and could potentially stretch right across it.
The strings, sometimes referred to as cracks in the universe, had not been detected since they were conceived, though there were a few ideas on how we might. When strings cross, for instance, it could provide us an opportunity to find them.
Tina Woods, serving as Healthy Longevity Champion for the National Innovation Center for Aging, sets forth her vision for a blueprint for healthy longevity for all. Her emphasis is on reaping the “longevity dividend” and achieving five additional years of healthy life expectancy while reducing health and wellbeing inequality. Woods elaborates on the role of emerging technologies like AI, machine learning, and advanced data analysis in comprehending and influencing biological systems related to aging. She also underscores the crucial role of lifestyle changes and the consideration of socio-economic factors in increasing lifespan. The talk also explores the burgeoning field of emotion AI and its application in developing environments for better health outcomes, with a mention of “Longevity Cities,” starting with a trial in Newcastle. In closing, Woods mentions the development of a framework for incentivizing businesses through measurement of their contribution to health in three areas: workforce health, consumer health through products and services, and community health. Woods envisions a future where businesses impacting health negatively are disincentivized, and concludes with the hope that the UK’s healthy longevity innovation mission can harness longevity science and data innovation to improve life expectancy.
00:00:00 — Introduction, National Innovation Center for Aging. 00:00:56 — Discussion on stagnating life expectancy and UK’s life sciences vision. 00:03:50 — Technological breakthroughs (including AI) in analyzing biological systems. 00:06:22 — Understanding what maintains health & wellbeing. 00:08:30 — Hype, hope, important of purpose. 00:10:00 — Psychological aging and “brain capital.“ 00:13:15 — Ageism — a barrier to progress in the field of aging. 00:15:46 — Health data, AI and wearables. 00:18:44 — Prevention is key, Health is an asset to invest in. 00:19:13 — Longevity Cities. 00:21:19 — Business for Health and industry incentives. 00:23:13 — Closing.
About the Speaker: Tina Woods is a social entrepreneur and system architect with a focus on health innovation at the intersection of science, technology, policy, and investment. She is the Founder and CEO of Collider Health and Business for Health, driving systemic change for better health through these platforms. She contributes to key UK health strategies and initiatives, like UKRI’s Healthy Ageing Industrial Strategy, and served as the Healthy Longevity Champion for the National Innovation Centre for Ageing. Woods has made significant contributions to AI in health and care, co-leading the Quantum Healthy Longevity Innovation Mission and authoring the book, “Live Longer with AI.” Previously, she served as the director of the All Party Parliamentary Group for Longevity secretariat. Woods is also the CEO & Founder of Collider Science, a social enterprise that encourages young people’s interest in science and technology. She holds a degree in genetics from Cornell University and an MBA from Bayes Business School in London.
You can think of quantum dots as artificial atoms that can be made in a lab! They have some of the same properties as atoms, such as having discrete energy levels (meaning they can only exist in certain distinct energy states, and they cannot have energy values between these specific levels) and being able to form molecules with other quantum dots. But they also have some unique features that make them useful for many applications, such as displays, solar cells, sensors, and medicine, which I shall discuss later in this story!
To grasp the workings of quantum dots, a bit of quantum mechanics knowledge comes in handy. Quantum mechanics teaches us that these tiny entities can possess only specific amounts of energy, and they transition between these energy levels by absorbing or emitting light. The energy of this light is determined by the difference in energy levels. In typical materials like metals or plastics, energy levels are closely packed, forming continuous bands where electrons can move freely, resulting in less specific light absorption or emission. However, in semiconductors like silicon or cadmium selenide, there’s a gap between these bands known as the “band gap.” Electrons can only jump from one band to another by interacting with light having an energy level that precisely matches the band gap, making semiconductors valuable for creating devices like transistors and LEDs.
From LED lights to medical imaging, quantum dots have many varied applications.
The creation of quantum dots earned its developers the Nobel Prize in Chemistry 2023, an invention that could have also been a contender for the Physics Prize. These tiny elements of nanotechnology, which are so miniature that their size dictates their properties, are today used in many useful and practical applications and have even been reported to direct surgeons as they tackle tricky tumor tissue.
Ben Dixon, a researcher in the Optical and Quantum Communications Technology Group, explains how the process works: “First, you need to generate pairs of specific entangled qubits (called Bell states) and transmit them in different directions across the network link to two separate quantum repeaters, which capture and store these qubits. One of the quantum repeaters then does a two-qubit measurement between the transmitted and stored qubit and an arbitrary qubit that we want to send across the link in order to interconnect the remote quantum systems. The measurement results are communicated to the quantum repeater at the other end of the link; the repeater uses these results to turn the stored Bell state qubit into the arbitrary qubit. Lastly, the repeater can send the arbitrary qubit into the quantum system, thereby linking the two remote quantum systems.”
To retain the entangled states, the quantum repeater needs a way to store them — in essence, a memory. In 2020, collaborators at Harvard University demonstrated holding a qubit in a single silicon atom (trapped between two empty spaces left behind by removing two carbon atoms) in diamond. This silicon “vacancy” center in diamond is an attractive quantum memory option. Like other individual electrons, the outermost (valence) electron on the silicon atom can point either up or down, similar to a bar magnet with north and south poles. The direction that the electron points is known as its spin, and the two possible spin states, spin up or spin down, are akin to the ones and zeros used by computers to represent, process, and store information. Moreover, silicon’s valence electron can be manipulated with visible light to transfer and store a photonic qubit in the electron spin state. The Harvard researchers did exactly this; they patterned an optical waveguide (a structure that guides light in a desired direction) surrounded by a nanophotonic optical cavity to have a photon strongly interact with the silicon atom and impart its quantum state onto that atom. Collaborators at MIT then showed this basic functionality could work with multiple waveguides; they patterned eight waveguides and successfully generated silicon vacancies inside them all.
Lincoln Laboratory has since been applying quantum engineering to create a quantum memory module equipped with additional capabilities to operate as a quantum repeater. This engineering effort includes on-site custom diamond growth (with the Quantum Information and Integrated Nanosystems Group); the development of a scalable silicon-nanophotonics interposer (a chip that merges photonic and electronic functionalities) to control the silicon-vacancy qubit; and integration and packaging of the components into a system that can be cooled to the cryogenic temperatures needed for long-term memory storage. The current system has two memory modules, each capable of holding eight optical qubits.
