Quantum physics can often make an object behave in seemingly impossible ways, such as tunneling through barriers as if they were not there or seemingly existing in two or more places at the same time. Now scientists have used quantum physics to create a battery capable of "superabsorption," meaning it absorbs energy more quickly the bigger it gets.
Previous work found that matter could act collectively in surprising ways due to quantum physics. For example, in "superradiance," a group of atoms charged up with energy can release a far more intense pulse of light than they could individually.
In the past decade, researchers have also discovered the reverse of superradiance was possible—superabsorption, with atoms cooperating to display enhanced absorption. However, until now superabsorption was seen for only small numbers of atoms.
Now scientists have developed a superabsorbent "quantum battery" that requires less charging time the larger it gets.
"The potential applications are the development of new types of batteries that can charge faster," says study lead author James Quach, a theoretical physicist at the University of Adelaide, in Australia. "In the same way that there has been a lot of recent investment in quantum computing—that is, using quantum effects to make computing faster—other operations about transferring energy or even harvesting energy can in principle be made faster by using quantum effects."
The new device consists of a reflective waferlike microcavity enclosing a semiconducting organic Lumogen F orange dye, which the researchers charged with energy using a laser. Ultrafast detectors helped the team monitor the way in which this dye charged and stored light energy at femtosecond resolution. As the microcavity size and the number of dye molecules increased, the charging time decreased.
Superabsorption can happen because of constructive interference, "when different waves add up to give a larger effect than either wave on its own," Quach explains. Given enough coherence—where the waves move in lockstep—and clusters of molecules "absorb light more efficiently than if each molecule were acting individually," he says. "The more molecules there are, the more pathways exist to interfere constructively."
Normally, quantum systems such as quantum computers experience disruption when their elements lose coherence, often due to unwanted interactions with their surroundings. As such, most quantum experiments require carefully isolated quantum systems to prevent such decoherence.
"However, in our research, we actually found that some amount of decoherence helped stabilize the energy stored in the quantum battery," Quach says.
Essentially, coherence may help the quantum battery charge fast, but decoherence keeps it from discharging this energy just as quickly. "The right amount of decoherence allows a device featuring coherence-enhanced absorption of light that does not then go on to also discharge with coherence-enhanced emission," Quach says.
Although keeping large quantum systems coherent may prove challenging, "as our quantum battery is not as fragile to environmental interaction as other quantum technologies, such as quantum computers, we are optimistic that we can scale up our experiment to larger devices," Quach says.
These prototype quantum batteries are charged with light. However, "there may be other ways to exploit the same quantum-interference effect in other scenarios," Quach says. "Our next steps are to explore how our results can be combined with other ways of storing and transferring energy to provide a device that could be practically useful. The key challenge, though, is to bridge the gap between the proof of principle here for a small device, and exploiting the same ideas in larger usable devices."
The scientists detailed their findings online 14 January in the journal Science Advances.
- Novel Quantum Emitter Provides Key Building Block for a Quantum ... ›
- How Quantum Computers Can Make Batteries Better - IEEE Spectrum ›