In a paper published in leading international science journal Nature today (15/11/07 UK time) the research team revealed a system that uses individual photons – single particles of light – as a ruler for microscopic distances.
The experiment was performed in the laboratory of Dr Geoff Pryde at Griffith University's Centre for Quantum Dynamics, by him and his PhD student Brendon Higgins. Centre Director, Professor Howard Wiseman, developed the theory, together with University of Sydney's Dr Stephen Bartlett and Macquarie University's Dr Dominic Berry.
Pryde’s apparatus used single photons, with each photon making a number of passes through the sample being measured.
Using just 36 photons making a total of 378 passes, the team was able to measure length differences less than one ten thousandth of the width of a human hair.
“This is an incredibly small amount of light.” said Pryde. “For comparison, scanning a barcode uses quadrillions of photons. Even the dim standby light on your DVD player shines out many trillions of photons a second.”
"Similar schemes based on interferometry – a technique using waves of electromagnetic radiation such as light – have been used for centuries to measure length, and other properties of objects, with great accuracy." said Wiseman.
"The key difference is we have done it in a way that gets as much information out of each pass of a photon through the sample as is allowed by Heisenberg's uncertainty principle. In this sense, it’s the best measurement possible – something that’s never been done before."
"The obvious applications are in making accurate measurements using less light than was previously thought possible. This is particularly important in fields such as medical research, as passing light through a biological sample can damage it," said Pryde.
So why do we need to measure with such accuracy"
"Measurement underpins all science, and through history we've seen that advances in precision measurement lead to unexpected scientific discoveries, which in turn lead to new technologies and applications," Pryde said.
"Old-style interferometers taught us that the Earth wasn’t moving through a mysterious substance called 'aether', but actually through a vacuum. This ultimately led to Einstein’s theory of relativity. We don’t know yet where this new technique will lead us.”
The team's next goal is to use more single photons and passes to get an even finer measurement.
"In principle this is possible, but there are some technological hurdles to overcome first!” said Pryde.
THE SCIENCE BEHIND THE DISCOVERY:
In the strange world of quantum physics, a photon can simultaneously take two different paths to the same destination. Where the photon goes next depends on the difference between the lengths of the two paths. If the length of one path is known, this allows scientists to measure the length of the other path with great accuracy. The novel feature of the Griffith experiment is to make the photon retrace the paths many times before detecting it. This amplifies the effect of the difference in path lengths. The same idea can also be applied to measuring other quantities like speed, frequency, and time.
The technique combined concepts from research in quantum computers (through Australia’s Centre for Quantum Computer Technology), in quantum control, and in quantum communication. “This is a great example of ideas coming together from different directions to make something new and exciting,” said Bartlett.
Jeannette Langan | EurekAlert!
Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center
A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology