Addictive Physics: Superconductivity Can Be Induced By Red Wine

Here’s another excuse you might find handy (or, maybe, not) for buying that bottle of red wine you always wanted: to do physics. Yes, that’s right, physics. Apparently, red wine can lead to better superconducting properties in certain alloys. This find was reported by a team of researchers based in Japan.

Superconductivity is a phenomenon exhibited by certain substances (pure metals or synthesized alloys) that display zero resistance to the flow of electric current. For example, if you cool mercury to 4.2 Kelvin (which is about minus 269 Celsius), it shows an abrupt decrease of electrical resistance. The resistance, in fact, suddenly goes to a value very close to zero.

Superconductivity sets at a critical temperature, Tc, at which the resistivity goes down to zero.

If a current is induced in the superconductor, it will be maintained without any supporting voltage for a very long, practically infinite, time. In case of normal conductors, like copper at room temperature, the current dies out, because of loss of energy by heating due to the resistance of the material. Interestingly, this property can be used to levitate magnets by exploting the so-called Meissner Effect. Watch the amazing video.

The focus of material sciences in recent times has been to find substances which show superconducting properties at higher temperatures. Such materials are called High Temperature Superconductors’ (HTc Superconductors). If a material is found such that it is superconducting at room temperatures, it will lead to huge leaps in electrical transport efficiency.  A few such materials are known, giving superconductivity at 30 K or -243 0C (LaBaCuO, for the science buffs) or at 92 K (YBaCuO). (The black slab in the above video is YBaCuO cooled by liquid nitrogen.)

Generally, bulk superconductivity is shown in materials after being treated appropriately. In a substance called Iron-Tellurium Sulphide (FeTe1-xSx), bulk superconductivity can be induced at quite high temperatures by immersion in water-ethanol mixture and oxygen annealing. (If the formulas bother you too much, just ignore them. These are not integral to the story.) The Japanese research team has discovered that superconductivity can be induced by heating the material in red-wine at 70 0C for 24 hours, after which it becomes superconducting at 9.9 K. More importantly, the quality of superconductor produced is high. (For science buffs, the shielding volume fraction, which is a measure of how good the superconductor is, is highest for FeTe0.8S0.2 boiled with red wine.)

The reason for this induction of superconductivity is not known.

The next time you see that expensive bottle of red wine, think superconductors’.  Here’s another bottle of champagne, err, wine in celebration of this discovery.

Quantum Breakthrough: Matter Guided through Optical Guides, Just Like Light Through Optical Fibers

It’s atoms now, and not only light. Researchers at ARC Center of Excellence for Quantum Atom Optics, Research School of Physics, ANU, have successfully guided supercooled Helium atoms through an optical guide made of a laser beam. This is the first ever successful at guiding matter waves.

Speckles, Modes and the Rest of the Basics:

When light is guided in an optical fiber, there can be many modes of transmission. These modes interfere and produce a speckle pattern’ on the screen after emerging from the fiber. The light can be adjusted so as to eliminate the speckle, which indicates that the light is in a single mode, or technically, coherent’. Scientists say that the light has the same phase factor’ throughout, which doesn’t vary with time.

Laser Speckle
Laser Speckle, the indication of multiple modes

There are many other coherent substances that can be made. One of them is known as the Bose-Einstein Condensate (BEC). During the 1920’s, Satyendranath Bose and Albert Einstein worked out the statistics of bosons and showed that, if cooled enough, they can be made to fall into a single giant ground state. In this state, any addition to the number density of the particles makes more particles fall into the ground state. This is, thus, called a Condensate’, appropriately named, Bose-Einstein Condensate’.

Bose Einstein Condensate
Bose-Einstein Condensate (The peaks indicate the number density of atoms in the ground state. Note how it rises with fall in temperature) (nK=nanoKelvin) (Courtesy: Colorado University)

BEC is a remarkable state of matter. Thousands of bosons (for example, Helium atoms) can condense and behave like a single super-atom. BEC physics is one of the richest and the present interest is primarily because BEC physics mimics that of superconductors.

The guiding of matter waves

What the team of researchers has achieved is this: They took a bunch of atoms and trapped them. Then,  they irradiated this with laser light pointing downwards towards gravity. This produced a speckled pattern.

As Ken Baldwin, one of the team members, reports

We have shown that when atoms in a vacuum chamber are guided inside a laser light beam, they too can create a speckle pattern – an image of which we have captured for the first time.

The BEC guide
The schematic for the BEC guide used by the researchers. (Courtesy: Nature)

The atoms were cooled to lower and lower temperatures, until the atoms formed the BEC. Since the BEC is a coherent state, with the lowering of the intensity of the laser light, the speckled pattern suddenly disappeared.

Team leader, Dr. Andrew Truscott, reported that:

The atoms … behaved more like waves than particles, forming a Bose-Einstein condensate (BEC).   When the BEC was loaded into the guide, the speckle pattern disappeared, showing that just one mode was being transmitted the single quantum wave.

Looking at the images and by measuring the arrival times of the atoms on the Multi-Channel Plate (MCP), the researchers could differentiate between a speckled, multi-mode transmission and a smooth, single-mode transmission.


Earlier it was only light that could be guided in a wave guide (here, the optical fiber). No longer is that true. This breakthrough demonstrates that it is possible to guide atoms in a BEC state in an optical guide (not glass). This will allow higher precision atom-interferometers.