Researchers from University of Twente proposed a theory that suggested reduced energy cost by appropriate timing of logical operations
The energy required per computation decreases as computers continue to reduce in size. However, digital devices may reach the theoretical limit for the minimum energy required for a single operation in the near future. Now, a team of researchers from the University of Twente proposed an approach to address this limit with the help of squeezed thermal states. These states allow the computer to operate at an effectively lower temperature as operations in these states consume less energy. The team suggested that energy savings can be achieved with current computer technology by leveraging squeezed states that emerge naturally in the thermal environment of a computer.
In 1961, Rolf Landauer, American-German physicist developed a simple thermodynamic model of a digital bit. In the model, the 0-state corresponds to the particle inhabiting the left-hand well and the 1-state corresponds to placement in the right-hand well. Landauer’s derivation assumes that the system is in thermal equilibrium. Recent studies have demonstrated that the Landauer limit may not hold when the bit is out of equilibrium. In the current research, the team developed a new strategy in which the bit remains in equilibrium and the surrounding environment (heat bath) is pushed out of equilibrium by thermally squeezing the bath. Squeezing relates to noise-related fluctuations that are distributed unevenly among the various dimensions of the system. In this squeezed state, the bath effectively oscillates between two temperatures that are above and one below the average temperature.
Operations such as piston movement are required to be performed when the bath is in its cold phase to lower the energy cost of erasing the bit. A colder bath means a colder particle that employs less pressure on the piston. Therefore, less work is needed to drive the particle to the left side. The team synchronized the operations with the temperature oscillations and found that the energy cost of erasing a bit has no lower bound, which suggests that more squeezing of the bath leads to lower energy cost. According to the researchers, this technique can offer energy savings for current computer bits that consume 1000 times more energy than the Landauer limit. The research was published in Physical Review Letters on January 28, 2019.