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Molecular fossils found in ancient sedimentary rocks have unveiled a lost world of primitive eukaryotes that dominated aquatic ecosystems from at least 1.6 billion to 800 million years ago.

The findings, published June 7 in Nature, come from laboratory analyses of rock samples from around the world that revealed remnants of primitive compounds called protosteroids. The majority of these molecules, which form in the process of creating steroids, were likely produced by primordial eukaryotes, relatively complex life-forms that today include animals, plants, algae and fungi, the researchers say.

Almost all eukaryotes produce molecules called steroids, like cholesterol, that are crucial components of cell membranes. Steroids dont degrade easily and their remnants can be detected in sedimentary rocks as molecular fossils.

The last common ancestor of all eukaryotes lived around 1.2 billion to more than 1.8 billion years ago. But scientists know almost nothing about the abundance, ecology and habitats of those early microorganisms. Molecular and physical fossils of eukaryotes dated to 800 million years ago have been found. But farther back in time, their physical fossils become scarce and molecular fossils of the steroids become undetectable. The existence of protosteroids had been predicted but it was unclear what they would look like or if they could even be detected until the researchers figured out a way to re-create those molecular footprints in the lab.

This study explains why we dont see footprints of these guys in the rocks, as researchers were looking for the wrong thing, says biologist Laura Katz, a biologist at Smith College in Northampton, Mass., who was not involved with the new work. It fills a void in the fossil records.

A dearth of obvious eukaryote fossils before 800 million years ago led scientists to speculate that the ecosystem at that time was dominated by bacteria. Alternatively, primordial eukaryotes may have simply lacked strength in numbers to leave behind detectable steroid remnants.

Some scientists had a different explanation: What if some intermediate molecule in the chemical pathway that produces modern steroids was actually the end product of the process in primordial eukaryotes? This theory had been proposed by the biochemist Konrad Bloch, who won the Nobel Prize in physiology or medicine in 1964 for discovering the biosynthetic pathway of cholesterol.

To test this, geochemist Jochen Brocks of the Australian National University in Canberra and colleagues artificially matured molecules made in the first few steps of steroid biosynthesis, including lanosterol and cycloartenol. That revealed what the compounds molecular fossils would look like. Then the researchers looked for these fossils in tarlike bitumens and oils extracted from ancient rocks from all over the world.

The researchers discovered a deluge of the protosteroids in samples ranging from deep to relatively shallow water environments. The oldest sample, dating back to 1.6 billion years ago, came from the Barney Creek Formation in Australia.

One of the greatest puzzles of early evolution is, why didnt our highly capable eukaryotic ancestors come to dominate the worlds ancient waterways? Where were they hiding? says Benjamin Nettersheim, a geobiologist at University of Bremen in Germany. We show that the protosteroid-producing microorganisms were hiding in plain sight and were in fact abundant in the worlds ancient oceans and lakes all along.

While most bacteria produce a different molecule, called hopanoids, some bacteria also have the chemical tools to kick-start protosteroid production. But these bacteria exist in niche environments, such as methane seeps and hydrothermal vents. And their molecular footprints have not been found in sediments older than 800 million years, leading the researchers to conclude that eukaryotes dominated the ancient ecosystems.

Konrad Bloch would have been delighted, had he lived, to see this, says MIT geobiologist Roger Summons, who wasnt involved in the study. This paper has elegantly confirmed his prediction that biosynthetic precursors to cholesterol reflect ancient lifes quest for improvement. (Bloch died in 2000.)

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Making these steroid precursors requires less oxygen and energy, so that may have given the primordial eukaryotes an advantage in thriving in early Earths harsh low oxygen conditions, the researchers propose (SN: 10/30/15).

If true, [this study] suggests that we may be able to examine the stepwise evolution of eukaryotes at [an] unprecedented level of detail, says evolutionary biologist Yosuke Hoshino of the GFZ German Research Centre for Geosciences in Potsdam, who was not involved in the study. This is such a great opportunity to understand the evolution of complex life, which biologists have always dreamed of.

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A Belgian research team says they have observed an anomalous bunching effect that appears to contradict our accepted understanding of the properties of photons, according to a new paper.

In physics, the notion that objects maintain pairs of complementary properties, not all of which can be observed or easily measured at the same time, is known as the complimentary principle. Proposed by physicist Niels Bohr, this principle can be summarized with the observation that objects in nature generally behave in one of two ways: like waves, or like particles.

Now, researchers with the Center for Quantum Information and Communication at the Ecole polytechnique de Bruxelles of Universit libre de Bruxelles in Belgium say they have made observations of photonic behavior that seemingly contradicts this long-held understanding.

The teams findings were published in the journal Nature Photonics.

Since light can be described as both a wave and as composed of particles containing no massi.e. photonswhich move at the speed of light, there is essentially no way to tell the difference between which paths photons follow in quantum interference experiments, which results in their clinging together or bunching.

This bunching behavior of photons, otherwise known as Boson bunching, is described by the team in their new paper as being among the most remarkable features of quantum physics.

One example involves what is known as the HongOuMandel effect, which describes a phenomenon in quantum optics involving two-photon interference first observed in the late 1980s by physicists at the University of Rochester. It occurs whenever a pair of identical single photons enter the separate input ports on a 1:1 beam splitter, and either cross the splitter or are reflected, resulting from quantum interference between their paths.

This effect takes its roots in the indistinguishability of identical photons, write authors Benoit Seron, Leonardo Novo, and Nicolas J. Cerf in their recent paper. Because of this, it is accepted based on past experimental verification that Boson bunching essentially vanishes as soon as photons can be distinguished, under conditions that include instances where they are present within distinct time bins or are observed to possess different polarizations.

Fundamentally, the bunching together of photons doesnt sit well within the framework of our classical view of physics, in terms of photons moving as particles following well-defined paths. Once their properties can be discerned by being traced back to their points of origin, or distinguished by factors like color or polarization, photons no longer engage in bunching; in short, bunching occurs to the greatest extent when photons remain indistinguishable and lessens the more discernable the particles become.

In the teams new research, led by Dr. Leonardo Novo, a theoretical scenario was imagined involving the bunching behaviors of seven photons with relation to the output paths of an interferometer. Given our current understanding of bunching, it should occur to the greatest extent when the same polarization occurs between all seven of the photons, since under these conditions they would be indistinguishable, and there would thus be no way to discern their paths as they pass through the interferometer.

However, the researchers found that in some cases the photon bunching phenomenon does not appear to behave as expected in every case: under conditions where photons attain a more clearly discernable polarization pattern and become partly distinguishable, there exist instances where photon bunching seems to show marked increases, rather than lessening.

The unexpected photonic behavior, Novo and the team writes, questions our understanding of multiparticle interference in the grey zone between indistinguishable bosons and classical particles.

According to the teams paper, they were able to upend this common understanding of the phenomenon with help from recent findings involving what is known as the theory of matrix permanents, noting that the presence of the odd boosting effect they came across in their theoretical study has real-world corollaries and is within reach of current photonic technology.

Although the observation is intriguing unto itself, the anomalous phenomenon of increased photon bunching potentially has applications within the quickly growing industry involving technologies that leverage quantum photonic principles. One of the most obvious examples is the construction of optical quantum computers, where a better understanding of photon bunching may prove very useful in the years ahead.

Novo and the teams paper, Boson bunching is not maximized by indistinguishable particles, appeared in the journal Nature Photonics on June 15, 2023.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email atmicah@thedebrief.org. Follow his work atmicahhanks.comand on Twitter:@MicahHanks.

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Unveiling the Mysteries of Quantum Metrology: A Comprehensive Guide

Quantum metrology, a relatively new and rapidly evolving field, has been garnering significant attention from scientists and researchers worldwide. This burgeoning area of study focuses on the application of quantum mechanics to the science of measurement, offering unprecedented levels of precision and accuracy. As our understanding of the quantum realm deepens, so too does our ability to harness its unique properties for a wide range of practical applications, from atomic clocks to cutting-edge sensors. In this comprehensive introduction, we will explore the fascinating world of quantum metrology, unveiling its mysteries and delving into its potential impact on our lives.

At its core, quantum metrology is built upon the principles of quantum mechanics, a branch of physics that deals with the behavior of matter and energy at the atomic and subatomic scales. Quantum mechanics is notorious for its counterintuitive and often baffling phenomena, such as superposition and entanglement. Superposition refers to the ability of quantum particles to exist in multiple states simultaneously, while entanglement describes the seemingly instantaneous connection between two particles, regardless of the distance separating them. These phenomena, while perplexing, offer a wealth of opportunities for advancing the field of metrology.

One of the most well-known applications of quantum metrology is in the development of atomic clocks, which are widely regarded as the most accurate timekeeping devices in existence. These clocks rely on the vibrations of atoms to measure time, with some models boasting an astonishing level of precision that would not lose a second over the course of millions of years. This remarkable accuracy is made possible by harnessing the principles of quantum mechanics, allowing scientists to fine-tune their measurements to an unprecedented degree.

Beyond atomic clocks, quantum metrology has the potential to revolutionize a wide range of industries through the development of advanced sensors and measurement devices. For example, researchers are currently exploring the use of quantum-enhanced sensors for applications such as gravitational wave detection, magnetic field sensing, and even medical imaging. These sensors leverage the unique properties of quantum particles to achieve levels of sensitivity and precision that are simply unattainable with classical methods.

As the field of quantum metrology continues to grow, so too does our understanding of the underlying principles that govern the quantum realm. One of the most promising areas of research in this regard is the study of quantum entanglement, which has the potential to unlock new levels of measurement precision and accuracy. By exploiting the correlations between entangled particles, scientists can effectively amplify their measurements, reducing the impact of noise and other sources of error. This technique, known as entanglement-enhanced metrology, has the potential to dramatically improve the performance of a wide range of measurement devices, from atomic clocks to advanced sensors.

Despite the tremendous progress that has been made in recent years, the world of quantum metrology remains shrouded in mystery, with many questions still left unanswered. As researchers continue to delve into the quantum realm, it is likely that new and unexpected discoveries will continue to emerge, reshaping our understanding of the universe and its underlying principles. In the meantime, the practical applications of quantum metrology are poised to have a profound impact on our lives, offering unprecedented levels of precision and accuracy in a wide range of fields.

In conclusion, the rapidly evolving field of quantum metrology holds great promise for the future, offering a wealth of opportunities for advancing our understanding of the quantum realm and its practical applications. From atomic clocks to cutting-edge sensors, the unique properties of quantum particles are poised to revolutionize the science of measurement, unlocking new levels of precision and accuracy that were once thought to be unattainable. As we continue to explore the mysteries of quantum metrology, we can look forward to a future where the boundaries of our knowledge are continually pushed, opening up new and exciting possibilities for scientific discovery and technological innovation.

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