Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Quantum 'paparazzi' film photons in the act of pairing up

Under certain conditions, two individual, indistinguishable photons will form a pair as a result of interference. This subtle quantum effect has been successfully imaged for the first time by Micha? Jachura and Rados?aw Chrapkiewicz, doctoral students at the UW Faculty of Physics (both shown here, in multiple copies and grouped into pairs on both sides of the measuring apparatus).
CREDIT: Source: UW Physics, R. Chrapkiewicz
Under certain conditions, two individual, indistinguishable photons will form a pair as a result of interference. This subtle quantum effect has been successfully imaged for the first time by Micha? Jachura and Rados?aw Chrapkiewicz, doctoral students at the UW Faculty of Physics (both shown here, in multiple copies and grouped into pairs on both sides of the measuring apparatus).

CREDIT: Source: UW Physics, R. Chrapkiewicz

Abstract:
In the quantum world of light, being distinguishable means staying lonely. Only those photons that are indistinguishable can wind up in a pair, through what is called Hong-Ou-Mandel interference. This subtle quantum effect has been successfully imaged for the first time by two doctoral students from the Faculty of Physics at the University of Warsaw.

Quantum 'paparazzi' film photons in the act of pairing up

Warsaw, Poland | Posted on April 22nd, 2015

Physicists have long known that photons can become bunched together. However, technological limitations have prevented the phenomenon from actually being observed directly. Only recently has this feat been achieved by two doctoral students from the Faculty of Physics at the University of Warsaw (UW). In an article just published in the renowned optical journal Optics Letters, Micha? Jachura and Rados?aw Chrapkiewicz presented a film sequence clearly showing photons forming pairs.

"We are the first to have filmed individual photons in a very interesting situation, 'pairing off' as a consequence of an effect known as Hong-Ou-Mandel two-photon interference," says doctoral student Micha? Jachura. He playfully expands upon this 'matrimonial' metaphor: "When carrying out our experiment we felt a bit like paparazzi. We were wielding an advanced camera of the latest generation, the exclusive 'venue' was the world of quantum mechanics, and the 'celebrities' we wanted to capture in the act were individual photons."

Interference is a phenomenon that can be observed when any wave - be it a light wave, a sound wave, or otherwise - passes through a barrier with more than one aperture (an experiment first carried out by the British physicist Thomas Young). Each aperture then acts as the source of a new wave, and a characteristic pattern of interference fringes forms on the other side of the screen placed behind the barrier. In the case of light waves, we see bright fringes where the wavefronts reinforce one another, and dark fringes where they cancel each other out.

Objects in the quantum world are characterized by a certain surprising property: they may behave either like particles or like waves, depending on how we observe them. If an individual photon behaves like a wave, it can pass through two apertures at the same time and interference fringes will form on the other side of the barrier (in other words, the single photon will interfere with itself). But such interference is only observed if the measurement system does not allow us to ascertain which aperture the photon passed through. If we make it possible to do so (for instance by placing a polarizing plate behind one of the apertures), the photon will immediately behave like a particle and the interference fringes disappear.

In 1987, a group of physicists from the University of Rochester (UR) predicted and observed a subtle quantum effect in an experimental setup involving a beam-splitting plate, which transmits some of the light that falls on it and reflects the remainder. The parameters of the plate can be chosen so that the probability of a given photon being reflected is equal to the probability of its passing through. If one photon is sent towards the plate from one side and another photon from the other side, there are four possible outcomes: both photons may be reflected, both transmitted, one of the photons may be reflected while the other is transmitted, or vice versa. The quantum-mechanical calculations performed by the UR physicists indicated that these various scenarios do indeed occur, but only when the photons impinging the plate are distinguishable, which means they are behaving like particles. But if the photons remain indistinguishable, interference will occur between them. As a result, the two photons become bunched into a pair and always appear together, on one side of the plate or the other.

"The Hong-Ou-Mandel effect had been observed before, but only by using photodiodes, which simply signaled the detection of a photon by sending out an electrical impulse. We were much better equipped, having at our disposal a highly advanced camera built by our research group. This camera, a bit similar to night-vision goggles, consists of an ultra-modern image intensifier and a very sensitive and a low-noise, fast sCMOS sensor. It proved to be so good that we were able to study the behavior of individual particles of light and managed to film their quantum interference," says doctoral student Rados?aw Chrapkiewicz, stressing that the camera design team also included Wojciech Wasilewski, PhD, and Jaros?aw Iwaszkiewicz, Eng. (both from the UW Faculty of Physics).

Using the camera and image intensifier, the UW Physics researchers managed to film the behavior of photons in two situations: when the photons being sent towards the beam-splitting plate were distinguishable and indistinguishable. In the former case the sequence of images shows individual green spots, which represent individual photons being registered, appearing randomly on opposite sides of the plate or together on one side or the other. But the moment the physicists purposefully eliminated the distinguishability, the photons immediately joined together in pairs and left the beam-splitting plate always on the same side, never separately.

"Managing to film two-photon interference is a very important result for quantum optics, as it means that from now on physicists will be able to directly observe spatial optical phenomena that involve single photons," stresses Prof. Tomasz Matulewicz, director of the Institute of Experimental Physics at the UW Faculty of Physics.

This research achievement, made possible by a PRELUDIUM grant from Poland's National Science Centre, represents an important step towards developing efficient methods of detecting quantum states of light and building super-resolution optical microscopes of a new type, capable of registering images using a small number of photons, therefore fully safe to use even with very delicate samples.

####

About Faculty of Physics at the University of Warsaw
Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 88 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students.

For more information, please click here

Contacts:
Rados?aw Chrapkiewicz

48-225-532-629

M.Sc. Micha? Jachura
Institute of Theoretical Physics, Faculty of Physics, University of Warsaw
tel. +48 22 55 32 629

Copyright © Faculty of Physics at the University of Warsaw

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

SCIENTIFIC PAPERS:

Faculty of Physics at the University of Warsaw website:

Press Office for the Faculty of Physics at the University of Warsaw:

Related News Press

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Imaging

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Physics

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Scientists use heat to create transformations between skyrmions and antiskyrmions January 12th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Videos/Movies

New X-ray imaging technique to study the transient phases of quantum materials December 29th, 2022

Solvent study solves solar cell durability puzzle: Rice-led project could make perovskite cells ready for prime time September 23rd, 2022

Scientists prepare for the world’s smallest race: Nanocar Race II March 18th, 2022

Visualizing the invisible: New fluorescent DNA label reveals nanoscopic cancer features March 4th, 2022

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Tools

First direct imaging of small noble gas clusters at room temperature: Novel opportunities in quantum technology and condensed matter physics opened by noble gas atoms confined between graphene layers January 12th, 2024

New laser setup probes metamaterial structures with ultrafast pulses: The technique could speed up the development of acoustic lenses, impact-resistant films, and other futuristic materials November 17th, 2023

Ferroelectrically modulate the Fermi level of graphene oxide to enhance SERS response November 3rd, 2023

The USTC realizes In situ electron paramagnetic resonance spectroscopy using single nanodiamond sensors November 3rd, 2023

Photonics/Optics/Lasers

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024

A battery’s hopping ions remember where they’ve been: Seen in atomic detail, the seemingly smooth flow of ions through a battery’s electrolyte is surprisingly complicated February 16th, 2024

Quantum nanoscience

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Bridging light and electrons January 12th, 2024

'Sudden death' of quantum fluctuations defies current theories of superconductivity: Study challenges the conventional wisdom of superconducting quantum transitions January 12th, 2024

Physicists ‘entangle’ individual molecules for the first time, hastening possibilities for quantum information processing: In work that could lead to more robust quantum computing, Princeton researchers have succeeded in forcing molecules into quantum entanglement December 8th, 2023

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project