探花直播 of Cambridge - optics

Switching 鈥榮pin鈥� on and off (and up and down) in quantum materials at room temperature

sc604 — Wed, 16 Aug 2023 15:00:00 +0000

Spin is the term for the intrinsic angular momentum of electrons, which is referred to as up or down. Using the up/down spin states of electrons instead of the 0 and 1 in conventional computer logic could transform the way in which computers process information. And sensors based on quantum principles could vastly improve our abilities to measure and study the world around us.

An international team of researchers, led by the 探花直播 of Cambridge, has found a way to use particles of light as a 鈥榮witch鈥� that can connect and control the spin of electrons, making them behave like tiny magnets that could be used for quantum applications.

探花直播researchers designed modular molecular units connected by tiny 鈥榖ridges鈥�. Shining a light on these bridges allowed electrons on opposite ends of the structure to connect to each other by aligning their spin states. Even after the bridge was removed, the electrons stayed connected through their aligned spins.

This level of control over quantum properties can normally only be achieved at ultra-low temperatures. However, the Cambridge-led team has been able to control the quantum behaviour of these materials at room temperature, which opens up a new world of potential quantum applications by reliably coupling spins to photons. 探花直播results are reported in the journal Nature.

Almost all types of quantum technology 鈥� based on the strange behaviour of particles at the subatomic level 鈥� involve spin. As they move, electrons usually form stable pairs, with one electron spin up and one spin down. However, it is possible to make molecules with unpaired electrons, called radicals. Most radicals are very reactive, but with careful design of the molecule, they can be made chemically stable.

鈥淭hese unpaired spins change the rules for what happens when a photon is absorbed and electrons are moved up to a higher energy level,鈥� said first author Sebastian Gorgon, from Cambridge鈥檚 Cavendish Laboratory. 鈥淲e鈥檝e been working with systems where there is one net spin, which makes them good for light emission and making LEDs.鈥�

Gorgon is a member of Professor Sir Richard Friend鈥檚 research group, where they have been studying radicals in organic semiconductors for light generation, and identified a stable and bright family of materials a few years ago. These materials can beat the best conventional OLEDs for red light generation.

鈥淯sing tricks developed by different fields was important,鈥� said Dr Emrys Evans from Swansea 探花直播, who co-led the research. 鈥� 探花直播team has significant expertise from a number of areas in physics and chemistry, such as the spin properties of electrons and how to make organic semiconductors work in LEDs. This was critical for knowing how to prepare and study these molecules in the solid state, enabling our demonstration of quantum effects at room temperature.鈥�

Organic semiconductors are the current state-of-the-art for lighting and commercial displays, and they could be a more sustainable alternative to silicon for solar cells. However, they have not yet been widely studied for quantum applications, such as quantum computing or quantum sensing.

鈥淲e鈥檝e now taken the next big step and linked the optical and magnetic properties of radicals in an organic semiconductor,鈥� said Gorgon. 鈥淭hese new materials hold great promise for completely new applications, since we鈥檝e been able to remove the need for ultra-cold temperatures.鈥�

鈥淜nowing what electron spins are doing, let alone controlling them, is not straightforward, especially at room temperature,鈥� said Friend, who co-led the research. 鈥淏ut if we can control the spins, we can build some interesting and useful quantum objects.鈥�

探花直播researchers designed a new family of materials by first determining how they wanted the electron spins to behave. Using this bottom-up approach, they were able to control the properties of the end material by using a building block method and changing the 鈥榖ridges鈥� between different modules of the molecule. These bridges were made of anthracene, a type of hydrocarbon.

For their 鈥榤ix-and-match鈥� molecules, the researchers attached a bright light-emitting radical to an anthracene molecule. After a photon of light is absorbed by the radical, the excitation spreads out onto the neighbouring anthracene, causing three electrons to start spinning in the same way. When a further radical group is attached to the other side of the anthracene molecules, its electron is also coupled, bringing four electrons to spin in the same direction.聽

鈥淚n this example, we can switch on the interaction between two electrons on opposite ends of the molecule by aligning electron spins on the bridge absorbing a photon of light,鈥� said Gorgon. 鈥淎fter relaxing back, the distant electrons remember they were together even after the bridge is gone.

鈥淚n these materials we鈥檝e designed, absorbing a photon is like turning a switch on. 探花直播fact that we can start to control these quantum objects by reliably coupling spins at room temperature could open up far more flexibility in the world of quantum technologies. There鈥檚 a huge potential here to go in lots of new directions.鈥�

鈥淧eople have spent years trying to get spins to reliably talk to each other, but by starting instead with what we want the spins to do and then the chemists can design a molecule around that, we鈥檝e been able to get the spins to align,鈥� said Friend. 鈥淚t鈥檚 like we鈥檝e hit the Goldilocks zone where we can tune the spin coupling between the building blocks of extended molecules.鈥�

探花直播advance was made possible through a large international collaboration 鈥� the materials were made in China, experiments were done in Cambridge, Oxford and Germany, and theory work was done in Belgium and Spain.

探花直播research was supported in part by the European Research Council, the European Union, the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI), and the Royal Society. Richard Friend is a Fellow of St John鈥檚 College, Cambridge.

聽

Reference:
Sebastian Gorgon et al. 鈥�Reversible spin-optical interface in luminescent organic radicals.鈥� Nature (2023). DOI: 10.1038/s41586-023-06222-1

Researchers have found a way to control the interaction of light and quantum 鈥榮pin鈥� in organic semiconductors, that works even at room temperature.

These new materials hold great promise for completely new applications, since we鈥檝e been able to remove the need for ultra-cold temperatures

Sebastian Gorgon

Artist's impression of aligned spins in an organic semiconductor

探花直播text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified.聽 All rights reserved. We make our image and video content available in a number of ways 鈥� as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Researchers devise a new path toward 鈥榪uantum light鈥�

sc604 — Thu, 02 Feb 2023 16:00:00 +0000

探花直播researchers, from the 探花直播 of Cambridge, along with colleagues from the US, Israel and Austria, developed a theory describing a new state of light, which has controllable quantum properties over a broad range of frequencies, up as high as X-ray frequencies. Their results are reported in the journal Nature Physics.

探花直播world we observe around us can be described according to the laws of classical physics, but once we observe things at an atomic scale, the strange world of quantum physics takes over. Imagine a basketball: observing it with the naked eye, the basketball behaves according to the laws of classical physics. But the atoms that make up the basketball behave according to quantum physics instead.

鈥淟ight is no exception: from sunlight to radio waves, it can mostly be described using classical physics,鈥� said lead author Dr Andrea Pizzi, who carried out the research while based at Cambridge鈥檚 Cavendish Laboratory. 鈥淏ut at the micro and nanoscale so-called quantum fluctuations start playing a role and classical physics cannot account for them.鈥�

Pizzi, who is currently based at Harvard 探花直播, worked with Ido Kaminer鈥檚 group at the Technion-Israel Institute of Technology and colleagues at MIT and the 探花直播 of Vienna to develop a theory that predicts a new way of controlling the quantum nature of light.

鈥淨uantum fluctuations make quantum light harder to study, but also more interesting: if correctly engineered, quantum fluctuations can be a resource,鈥� said Pizzi. 鈥淐ontrolling the state of quantum light could enable new techniques in microscopy and quantum computation.鈥�

One of the main techniques for generating light uses strong lasers. When a strong enough laser is pointed at a collection of emitters, it can rip some electrons away from the emitters and energise them. Eventually, some of these electrons recombine with the emitters they were extracted from, and the excess energy they absorbed is released as light. This process turns the low-frequency input light into high-frequency output radiation.

鈥� 探花直播assumption has been that all these emitters are independent from one another, resulting in output light in which quantum fluctuations are pretty featureless,鈥� said Pizzi. 鈥淲e wanted to study a system where the emitters are not independent, but correlated: the state of one particle tells you something about the state of another. In this case, the output light starts behaving very differently, and its quantum fluctuations become highly structured, and potentially more useful.鈥�

To solve this type of problem, known as a many body problem, the researchers used a combination of theoretical analysis and computer simulations, where the output light from a group of correlated emitters could be described using quantum physics.

探花直播theory, whose development was led by Pizzi and Alexey Gorlach from the Technion, demonstrates that controllable quantum light can be generated by correlated emitters with a strong laser. 探花直播method generates high-energy output light, and could be used to engineer the quantum-optical structure of X-rays.

鈥淲e worked for months to get the equations cleaner and cleaner until we got to the point where we could describe the connection between the output light and the input correlations with just one compact equation. As a physicist, I find this beautiful,鈥� said Pizzi. 鈥淟ooking forward, we would like to collaborate with experimentalists to provide a validation of our predictions. On the theory side of things, our work suggests many-body systems as a resource for generating quantum light, a concept that we want to investigate more broadly, beyond the setup considered in this work.鈥�

探花直播research was supported in part by the Royal Society. Andrea Pizzi is a Junior Research Fellow at Trinity College, Cambridge.

聽

Reference:
Andrea Pizzi et al. 鈥�Light emission from strongly driven many-body systems.鈥� Nature Physics (2023). DOI: 10.1038/s41567-022-01910-7

Researchers have theorised a new mechanism to generate high-energy 鈥榪uantum light鈥�, which could be used to investigate new properties of matter at the atomic scale.

David Wall via Getty Images

Design of a glowing fractal pattern with stars floating on a black background

探花直播text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright 漏探花直播 of Cambridge and licensors/contributors as identified.聽 All rights reserved. We make our image and video content available in a number of ways 鈥� as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Two-dimensional material could store quantum information at room temperature

sc604 — Fri, 11 Feb 2022 11:01:00 +0000

Quantum memory is a major building block to be addressed in the building of a quantum internet, where quantum information is securely stored and sent via photons, or particles of light.

Researchers from the Cavendish Laboratory at the 探花直播 of Cambridge, in collaboration with colleagues from UT聽Sydney in Australia, have identified a two-dimensional material, hexagonal boron nitride, that can emit single photons from atomic-scale defects in its structure at room temperature.

探花直播researchers discovered that the light emitted from these isolated defects gives information about a quantum property that can be used to store quantum information, called spin, meaning the material could be useful for quantum applications. Importantly, the quantum spin can be accessed via light and at room temperature.

探花直播finding could eventually support scalable quantum networks built from two-dimensional materials that can operate at room temperature. 探花直播results are reported in the journal Nature Communications.

Future communication networks will use single photons to send messages around the world, which will lead to more secure global communication technologies.

Computers and networks built on the principles of quantum mechanics would be both far more powerful and more secure than current technologies. However, in order to make such networks possible, researchers need to develop reliable methods of generating single, indistinguishable photons as carriers of information across quantum networks.

鈥淲e can send information from one place to another using photons, but if we鈥檙e going to build real quantum networks, we need to send information, store it and send it somewhere else,鈥� said Dr Hannah Stern from Cambridge鈥檚 Cavendish Laboratory, the study鈥檚 co-first author, along with Qiushi Gu and Dr John Jarman. 鈥淲e need materials that can hold onto quantum information for a certain amount of time at room temperature, but most current material platforms we鈥檝e got are challenging to make and only work well at low temperatures.鈥�

Hexagonal boron nitride is a two-dimensional material that is grown by chemical vapour deposition in large reactors. It鈥檚 cheap and scalable. Recent efforts have revealed the presence of single photon emitters and the presence of a dense ensemble of optically accessible spins, but not individually isolated spin-photon interfaces operating under ambient conditions.

鈥淯sually, it鈥檚 a pretty boring material that鈥檚 normally used as an insulator,鈥� said Stern, who is a Junior Research Fellow at Trinity College. 鈥淏ut we found that there are defects in this material that can emit single photons, which means it could be used in quantum systems. If we can get it to store quantum information in spin, then it鈥檚 a scalable platform.鈥�

Stern and her colleagues set up a hexagon boron nitride sample near a tiny gold antenna and a magnet of set strength. By firing a laser at the sample at room temperature, they were able to observe lots of different magnetic field-dependent responses on the light being emitted from the material.

探花直播researchers found that when they shone the laser on the material, they were able to manipulate the spin, or inherent angular momentum, of the defects, and use the defects as a way of storing quantum information.

鈥淭ypically, the signal is always the same in these systems, but in this case, the signal changes depending on the particular defect we鈥檙e studying, and not all defects show a signal, so there is a lot to still discover,鈥� said co-first author Qiushi Gu. 鈥淭here鈥檚 a lot of variation across the material, like a blanket draped over a moving surface 鈥� you see lots of ripples, and they鈥檙e all different.鈥�

Professor Mete Atature, who supervised the work, adds 鈥渘ow that we have identified optically accessible isolated spins at room temperature in this material, the next steps will be to understand their photophysics in detail and explore the operation regimes for possible applications including information storage and quantum sensing. There will be a stream of fun physics following this work.鈥�

探花直播research was supported in part by the European Research Council. Mete Atature聽is a Fellow of St John's College, Cambridge.聽

Reference:
Hannah L. Stern, Quishi Gu, John Jarman, et al. 鈥�Room-temperature optically detected magnetic resonance of single defects in hexagonal boron nitride.鈥� Nature Communications (2022). DOI: 10.1038/s41467-022-28169-z

Researchers have identified a two-dimensional material that could be used to store quantum information at room temperature.

There are defects in this material that can emit single photons, which means it could be used in quantum systems

Hannah Stern

Qiushi Gu

Artistic rendition of isolated spins on hexagonal boron nitride under an optical microscope

Yes

Colour-changing magnifying glass gives clear view of infrared light

sc604 — Thu, 02 Dec 2021 19:00:00 +0000

Detecting light beyond the visible red range of our eyes is hard to do, because infrared light carries so little energy compared to ambient heat at room temperature. This obscures infrared light unless specialised detectors are chilled to very low temperatures, which is both expensive and energy-intensive.

Now researchers led by the 探花直播 of Cambridge have demonstrated a new concept in detecting infrared light, showing how to convert it into visible light, which is easily detected.

In collaboration with colleagues from the UK, Spain and Belgium, the team used a single layer of molecules to absorb the mid-infrared light inside their vibrating chemical bonds. These shaking molecules can donate their energy to visible light that they encounter, 鈥榰pconverting鈥� it to emissions closer to the blue end of the spectrum, which can then be detected by modern visible-light cameras.

探花直播results, reported in the journal Science, open up new low-cost ways to sense contaminants, track cancers, check gas mixtures, and remotely sense the outer universe.

探花直播challenge faced by the researchers was to make sure the quaking molecules met the visible light quickly enough. 鈥淭his meant we had to trap light really tightly around the molecules, by squeezing it into crevices surrounded by gold,鈥� said first author Angelos Xomalis from Cambridge鈥檚 Cavendish Laboratory.

探花直播researchers devised a way to sandwich single molecular layers between a mirror and tiny chunks of gold, only possible with 鈥榤eta-materials鈥� that can twist and squeeze light into volumes a billion times smaller than a human hair.

鈥淭rapping these different colours of light at the same time was hard, but we wanted to find a way that wouldn鈥檛 be expensive and could easily produce practical devices,鈥� said co-author Dr Rohit Chikkaraddy from the Cavendish Laboratory, who devised the experiments based on his simulations of light in these building blocks.

鈥淚t鈥檚 like listening to slow-rippling earthquake waves by colliding them with a violin string to get a high whistle that鈥檚 easy to hear, and without breaking the violin,鈥� said Professor Jeremy Baumberg of the NanoPhotonics Centre at Cambridge鈥檚 Cavendish Laboratory, who led the research.

探花直播researchers emphasise that while it is early days, there are many ways to optimise the performance of these inexpensive molecular detectors, which then can access rich information in this window of the spectrum.

From astronomical observations of galactic structures to sensing human hormones or early signs of invasive cancers, many technologies can benefit from this new detector advance.

探花直播research was conducted by a team from the 探花直播 of Cambridge, KU Leuven, 探花直播 College London (UCL), the Faraday Institution, and Universitat Polit猫cnica de Val猫ncia.

探花直播research is funded as part of a UK Engineering and Physical Sciences Research Council (EPSRC) investment in the Cambridge NanoPhotonics Centre, as well as the European Research Council (ERC), Trinity College Cambridge and KU Leuven.

Jeremy Baumberg is a Fellow of Jesus College, Cambridge.聽

Reference:
Angelos Xomalis et al. 鈥楧etecting mid-infrared light by molecular frequency upconversion with dual-wavelength hybrid nanoantennas鈥�, Science (2021). DOI: 10.1126/science.abk2593

By trapping light into tiny crevices of gold, researchers have coaxed molecules to convert invisible infrared into visible light, creating new low-cost detectors for sensing.

It鈥檚 like listening to slow-rippling earthquake waves by colliding them with a violin string to get a high whistle that鈥檚 easy to hear, and without breaking the violin

Jeremy Baumberg

NanoPhotonics Cambridge /Ermanno Miele, Jeremy Baumberg

Nano-antennas convert invisible infrared into visible light

Yes

Atom swapping could lead to ultra-bright, flexible next generation LEDs

sc604 — Mon, 07 Jun 2021 15:25:23 +0000

探花直播researchers, led by the 探花直播 of Cambridge and the Technical 探花直播 of Munich, found that by swapping one out of every 1,000 atoms of one material for another, they were able to triple the luminescence of a new material class of light emitters known as halide perovskites. 聽

This 鈥榓tom swapping鈥�, or doping, causes the charge carriers to get stuck in a specific part of the material鈥檚 crystal structure, where they recombine and emit light. 探花直播results, reported in the Journal of the American Chemical Society, could be useful for low-cost printable and flexible LED lighting, displays for smartphones or cheap lasers.

Many everyday applications now use light-emitting devices (LEDs), such as domestic and commercial lighting, TV screens, smartphones and laptops. 探花直播main advantage of LEDs is they consume far less energy than older technologies.

Ultimately, also the entirety of our worldwide communication via the internet is driven by optical signals from very bright light sources that within optical fibres carry information at the speed of light across the globe.

探花直播team studied a new class of semiconductors called halide perovskites in the form of nanocrystals which measure only about a ten-thousandth of the thickness of a human hair. These 鈥榪uantum dots鈥� are highly luminescent materials: the first high-brilliance QLED TVs incorporating quantum dots recently came onto the market.

探花直播Cambridge researchers, working with Daniel Congreve鈥檚 group at Harvard, who are experts in the fabrication of quantum dots, have now greatly improved the light emission from these nanocrystals. They substituted one out of every one thousand atoms with another 鈥� swapping lead for manganese ions 鈥� and found the luminescence of the quantum dots tripled.

A detailed investigation using laser spectroscopy revealed the origin of this observation. 鈥淲e found that the charges collect together in the regions of the crystals that we doped,鈥� said Sascha Feldmann from Cambridge鈥檚 Cavendish Laboratory, the study鈥檚 first author. 鈥淥nce localised, those energetic charges can meet each other and recombine to emit light in a very efficient manner.鈥�

鈥淲e hope this fascinating discovery: that even smallest changes to the chemical composition can greatly enhance the material properties, will pave the way to cheap and ultrabright LED displays and lasers in the near future,鈥� said senior author Felix Deschler, who is jointly affiliated at the Cavendish and the Walter Schottky Institute at the Technical 探花直播 of Munich.

In the future, the researchers hope to identify even more efficient dopants which will help make聽these advanced light technologies accessible to every part of the world.

聽

Reference:
Sascha Feldmann et al. 鈥�Charge carrier localization in doped perovskite nanocrystals enhances radiative recombination.鈥�, Journal of the American Chemical Society (2021). DOI: 10.1021/jacs.1c01567

An international group of researchers has developed a new technique that could be used to make more efficient low-cost light-emitting materials that are flexible and can be printed using ink-jet techniques.

Ella Maru Studio

Artist鈥檚 impression of glowing halide perovskite nanocrystals

Yes

Cambridge researchers awarded European Research Council funding

sc604 — Wed, 01 Apr 2020 13:19:46 +0000

One hundred and eighty-five senior scientists from across Europe were awarded grants in today鈥檚 announcement, representing a total of 鈧�450 million in research funding. 探花直播UK has 34 grantees in this year鈥檚 funding round, the second-most of any ERC participating country.

ERC grants are awarded through open competition to projects headed by starting and established researchers, irrespective of their origins, who are working or moving to work in Europe. 探花直播sole criterion for selection is scientific excellence.

ERC Advanced Grants are designed to support excellent scientists in any field with a recognised track record of research achievements in the last ten years.

Professors Mete Atat眉re and Jeremy Baumberg, both based at Cambridge鈥檚 Cavendish Laboratory, work on diverse ways to create new and strange interactions of light with matter that is built from tiny nano-sized building blocks.

Baumberg鈥檚 PICOFORCE project traps light down to the size of individual atoms which will allow him to invent new ways of tugging them, levitating them, and putting them together. Such work uncovers the mysteries of how molecules and metals interact, crucial for creating energy sustainably, storing it, and developing electronics that can switch with thousands of times less power need than currently.

"This funding recognises the huge need for fundamental science to advance our knowledge of the world 鈥� only the most imaginative and game-changing science gets such funding," said Baumberg.

Atat眉re鈥檚 project, PEDESTAL, investigates diamond as a material platform for quantum networks. What gives gems their colour also turns out to be interesting candidates for quantum computing and communication technologies. By developing large-scale diamond-semiconductor hybrid quantum devices, the project aims to demonstrate high-rate and high-fidelity remote entanglement generation, a building block for a quantum internet.

" 探花直播impact of ERC funding on my group鈥檚 research had been incredible in the last 12 years, through Starting and Consolidator grants. I am very happy that with this new grant we as UK scientists can continue to play an important part in the vibrant research culture of Europe," said Atat眉re.

Professor Judith Driscoll from Cambridge鈥檚 Department of Materials Science & Metallurgy was also awarded ERC funding for her work on nanostructured electronic materials. She is also spearheading joint work of her team, as well as those of Baumberg and Atat眉re, on low-energy IT devices.

"My approach uses a different way of designing and creating oxide nano-scale film structures with different materials to both create new electronic device functions as well as much more reliable and uniform existing functions," she said. "Cambridge is a fantastic place that enables all our approaches to come together, driven by cohorts of inspirational young researchers in our UK-funded Centre for Doctoral Training in Nanoscience and Nanotechnology 鈥� the NanoDTC."

Professor John Robb from Cambridge鈥檚 Department of Archaeology was awarded an ERC grant for the ANCESTORS project on the politics of death in prehistoric Europe. 探花直播project takes the methods developed in the 鈥楢fter the Plague鈥� project and the taphonomy methods developed in the Scaloria Cave project and apply them to a major theoretical problem in European prehistory - the nature of community and the rise of inequality.

"This project is really exciting and I鈥檒l be working with wonderful colleagues Dr Christiana 鈥楩reddi鈥� Scheib at the 探花直播 of Tartu and Dr Mary Anne Tafuri at Sapienza 探花直播 of Rome," said Robb. " 探花直播results will allow us to evaluate for the first time how inequality affected lives in prehistoric Europe and what role ancestors played in it."

Four researchers at the 探花直播 of Cambridge have won advanced grants from the European Research Council (ERC), Europe鈥檚 premier research funding body.

Yes

Nanowires replace Newton鈥檚 famous glass prism

sc604 — Thu, 05 Sep 2019 18:00:00 +0000

探花直播device, made from a single nanowire 1000 times thinner than a human hair, is the smallest spectrometer ever designed. It could be used in potential applications such as assessing the freshness of foods, the quality of drugs, or even identifying counterfeit objects, all from a smartphone camera. Details are reported in the journal Science.

In the 17^th century, Isaac Newton, through his observations on the splitting of light by a prism, sowed the seeds for a new field of science studying the interactions between light and matter 鈥� spectroscopy. Today, optical spectrometers are essential tools in industry and almost all fields of scientific research. Through analysing the characteristics of light, spectrometers can tell us about the processes within galactic nebulae, millions of light years away, down to the characteristics of protein molecules.

However, even now, the majority of spectrometers are based around principles similar to what Newton demonstrated with his prism: the spatial separation of light into different spectral components. Such a basis fundamentally limits the size of spectrometers in respect: they are usually bulky and complex, and challenging to shrink to sizes much smaller than a coin. Four hundred years after Newton, 探花直播 of Cambridge researchers have overcome this challenge to produce a system up to a thousand times smaller than those previously reported.

探花直播Cambridge team, working with colleagues from the UK, China and Finland, used a nanowire whose material composition is varied along its length, enabling it to be responsive to different colours of light across the visible spectrum. Using techniques similar to those used for the manufacture of computer chips, they then created a series of light-responsive sections on this nanowire.

鈥淲e engineered a nanowire that allows us to get rid of the dispersive elements, like a prism, producing a far simpler, ultra-miniaturised system than conventional spectrometers can allow,鈥� said first author Zongyin Yang from the Cambridge Graphene Centre. 鈥� 探花直播individual responses we get from the nanowire sections can then be directly fed into a computer algorithm to reconstruct the incident light spectrum.鈥�

鈥淲hen you take a photograph, the information stored in pixels is generally limited to just three components 鈥� red, green, and blue,鈥� said co-first author Tom Albrow-Owen. 鈥淲ith our device, every pixel contains data points from across the visible spectrum, so we can acquire detailed information far beyond the colours which our eyes can perceive. This can tell us, for instance, about chemical processes occurring in the frame of the image.鈥�

鈥淥ur approach could allow unprecedented miniaturisation of spectroscopic devices, to an extent that could see them incorporated directly into smartphones, bringing powerful analytical technologies from the lab to the palm of our hands,鈥� said Dr Tawfique Hasan, who led the study.

One of the most promising potential uses of the nanowire could be in biology. Since the device is so tiny, it can directly image single cells without the need for a microscope. And unlike other bioimaging techniques, the information obtained by the nanowire spectrometer contains a detailed analysis of the chemical fingerprint of each pixel.

探花直播researchers hope that the platform they have created could lead to an entirely new generation of ultra-compact spectrometers working from the ultraviolet to the infrared range. Such technologies could be used for a wide range of consumer, research and industrial applications, including in lab-on-a-chip systems, biological implants, and smart wearable devices.

探花直播Cambridge team has filed a patent on the technology, and hopes to see real-life applications within the next five years.

Reference:
Zongyin Yang et al. 鈥楽ingle nanowire spectrometers.鈥� Science (2019). DOI: 10.1126/science.aax8814

Scientists have designed an ultra-miniaturised device that could image single cells without the need for a microscope or make chemical fingerprint analysis possible from within a smartphone camera.聽

Our approach could bring powerful analytical technologies from the lab to the palm of our hands

Tawfique Hasan

Ella Maru Studio

Artist's impression of single-nanowire spectrometer

Yes

Physicists get thousands of semiconductor nuclei to do 鈥榪uantum dances鈥� in unison

Anonymous — Fri, 22 Feb 2019 12:46:40 +0000

Quantum dots are crystals made up of thousands of atoms, and each of these atoms interacts magnetically with the trapped electron.聽 If left alone to its own devices, this interaction of the electron with the nuclear spins, limits the usefulness of the electron as a quantum bit - a qubit.

Led by Professor Mete Atat眉re from Cambridge's聽Cavendish Laboratory, the researchers are exploiting the laws of quantum physics and optics to investigate computing, sensing or communication applications.

鈥淨uantum dots offer an ideal interface, as mediated by light, to a system where the dynamics of individual interacting spins could be controlled and exploited,鈥� said聽Atat眉re, who is a Fellow of St John's College. 鈥淏ecause the nuclei randomly 鈥榮teal鈥� information from the electron they have traditionally been an annoyance, but we have shown we can harness them as a resource.鈥�

探花直播Cambridge team found a way to exploit the interaction between the electron and the thousands of nuclei using lasers to 鈥榗ool鈥� the nuclei to less than 1 milliKelvin, or a thousandth of a degree above the absolute zero temperature. They then showed they can control and manipulate the thousands of nuclei as if they form a single body in unison, like a second qubit. This proves the nuclei in the quantum dot can exchange information with the electron qubit and can be used to store quantum information as a memory device.聽探花直播results are reported in the journal Science.

Quantum computing aims to harness fundamental concepts of quantum physics, such as entanglement and superposition principle, to outperform current approaches to computing and could revolutionise technology, business and research.聽 Just like classical computers, quantum computers need a processor, memory, and a bus to transport the information backwards and forwards. 探花直播processor is a qubit which can be an electron trapped in a quantum dot, the bus is a single photon that these quantum dots generate and are ideal for exchanging information. But the missing link for quantum dots is quantum memory.

Atat眉re said: 鈥淚nstead of talking to individual nuclear spins, we worked on accessing collective spin waves by lasers. This is like a stadium where you don鈥檛 need to worry about who raises their hands in the Mexican wave going round, as long as there is one collective wave because they all dance in unison.

鈥淲e then went on to show that these spin waves have quantum coherence. This was the missing piece of the jigsaw and we now have everything needed to build a dedicated quantum memory for every qubit.鈥�

In quantum technologies, the photon, the qubit and the memory need to interact with each other in a controlled way.聽 This is mostly realised by interfacing different physical systems to form a single hybrid unit which can be inefficient.聽探花直播researchers have been able to show that in quantum dots, the memory element is automatically there with every single qubit.

Dr Dorian Gangloff, one of the first authors of the paper and a Fellow at St John鈥檚, said the discovery will renew interest in these types of semiconductor quantum dots. Dr Gangloff explained: 鈥淭his is a Holy Grail breakthrough for quantum dot research 鈥� both for quantum memory and fundamental research; we now have the tools to study dynamics of complex systems in the spirit of quantum simulation.鈥�

探花直播long term opportunities of this work could be seen in the field of quantum computing. Last month, IBM launched the world鈥檚 first commercial quantum computer, and the Chief Executive of Microsoft has said quantum computing has the potential to 鈥榬adically reshape the world鈥�.聽

Gangloff said: 鈥� 探花直播impact of the qubit could be half a century away but the power of disruptive technology is that it is hard to conceive of the problems we might open up 鈥� you can try to think of it as known unknowns but at some point you get into new territory. We don鈥檛 yet know the kind of problems it will help to solve which is very exciting.鈥�

Reference:
D. A. Gangloff聽et al. 'Quantum interface of an electron and a nuclear ensemble.' Science (2019). DOI:聽10.1126/science.aaw2906

Originally published on the St John's College website.

A team of Cambridge researchers have found a way to control the sea of nuclei in semiconductor quantum dots so they can operate as a quantum memory device.

This is like a stadium where you don鈥檛 need to worry about who raises their hands in the Mexican wave going round, as long as there is one collective wave because they all dance in unison

Mete Atat眉re

探花直播 of Cambridge

Theoretical ESR spectrum buildup as a function of two-photon detuning 未 and drive time 蟿, for a Rabi frequency of 惟 = 3.3 MHz on the central transition.

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