Unlocking the Chills: Exploring the Extreme Cold Limits of Indium for a Potential New State of Matter

• When sufficiently chilled, matter can transform into unusual phases that seem to be one thing, yet act like another.
• Indium is part of a category of elements that has never been brought to an ultracold state previously, but a group of scientists has at last succeeded in cooling it to a temperature just shy of absolute zero.
• Future applications of ultracool indium atoms might include predicting the behavior of novel materials, powering exceptionally accurate atomic clocks, among other things.

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When physics encounters extreme cold, it can be particularly fascinating.

Matter exists in more than just three forms. Alongside solids, liquids, and gases, there are extraordinary states of matter such as supersolids (which exhibit properties of both solids and liquids) and quantum fluids (composed of light particles that collectively mimic a fluid). Numerous varieties of these states of matter are produced in laboratories under conditions like extreme cold.

Presently, ultracold indium may foster a new state of matter that appears to belong in science fiction. This highly lustrous element is easily manipulated, softer than lead, highly ductile (maintaining pliability without becoming rigid), and malleable (can be hammered and pressed extensively without fracturing). It also retains these characteristics even at exceptionally low temperatures.

In contrast to alkali, alkaline earth, and lanthanide elements that have previously been cryogenically frozen, indium is a triel element, situated in Group 13 of the periodic table. Triel elements are recognized for their versatility, making them suitable for ultracold physics and other exceptional quantum states, yet none had ever been brought to such low temperatures until now.

A team of researchers from Duke University sought to determine if they could lower the temperature of indium to a point where its atoms could be rearranged to form a new state of matter. Recently, they achieved just that.

“[Indium’s] unique combination [of characteristics], not found in alkalis and alkaline earths, would permit an extraordinary level of quantum control,” stated the Duke research group in a study recently uploaded to the preprint database arXiv.

By bombarding thousands of atoms of a prevalent indium isotope with lasers and electromagnetic forces, the researchers successfully lowered the temperature to 15 millionths of one Kelvin. To illustrate just how cold this is, zero Kelvin equates to -273.15 degrees Celsius or -457.87 degrees Fahrenheit, often referred to as absolute zero.

Although no novel phases of matter have yet been created using indium, researchers already have numerous ideas about what they might look like. They speculate that whatever this new state may turn out to be, it could potentially be utilized in quantum clocks—the most precise clocks on the planet, powered by ultracool ions—and material simulations, which leverage ultracool atoms to forecast the behavior of a material and how to address any challenges that might emerge in its fabrication and application.

Another prospective use for ultracool indium would be in a Bose-Einstein condensate, or BEC. This state of matter can be achieved when a gas comprised of bosons (a category of subatomic particles that includes photons and Higgs bosons) is cooled near absolute zero, enabling the creation of technology such as atomic lasers and various types of sensors.

“Our methods are widely applicable to the triel elements, which possess a comparable energy level configuration to indium,” the researchers noted in the study. “These achievements create the foundation for [revolutionary] quantum science experiments.”