A Maxwell Demon Model Connecting Information and Thermodynamics

In the past decades several theoretical Maxwell＇s demon models have been proposed to exhibit effects such as refrigerating, doing work at the cost of information, and some experiments have been carried out to realize these effects. We propose a model with a two-level demon, information represented by a sequence of bits, and two heat reservoirs. The reservoir that the demon is interacting with depends on the bit. When the temperature difference between the two heat reservoirs is large enough, the information can be erased. On the other hand, when the information is pure enough, heat transfer from one reservoir to the other can happen, resulting in the effect of refrigeration. Genuine examples of such a system are discussed.

Relating Maxwell's demon and quantitative analysis of information leakage for practical imperative programs

Shannon observed the relation between information entropy and Maxwell demon experiment to come up with information entropy formula. After that, Shannon＇s entropy formula is widely used to measure information leakage in imperative programs. But in the present work, our aim is to go in a reverse direction and try to find possible Maxwell＇s demon experimental setup for contemporary practical imperative programs in which variations of Shannon＇s entropy formula has been applied to measure the information leakage. To establish the relation between the second principle of thermodynamics and quantitative analysis of information leakage, present work models contemporary variations of imperative programs in terms of Maxwell＇s demon experimental setup. In the present work five contemporary variations of imperative program related to information quantification are identified. They are： （i） information leakage in imperative program, （ii） imperative multi- threaded program, （iii） point to point leakage in the imperative program, （iv） imperative program with infinite observation, and （v） imperative program in the SOA-based environment. For these variations, minimal work required by an attacker to gain the secret is also calculated using historical Maxwell＇s demon experiment. To model the experimental setup of Maxwell＇s demon, non-interference security policy is used. In the present work, imperative programs with one-bit secret information have been considered to avoid the complexity. The findings of the present work from the history of physics can be utilized in many areas related to information flow of physical computing, nano-computing, quantum computing, biological computing, energy dissipation in computing, and computing power analysis.

Supplemental Materials: Realization of Quantum Maxwell's Demon with Solid-State Spins

We report experimental realization of a quantum version of Maxwell＇s demon using solid state spins where the information acquiring and feedback operations by the demon are achieved through conditional quantum gates.A unique feature of this implementation is that the demon can start in a quantum superposition state or in an entangled state with an ancilla observer. Through quantum state tomography, we measure the entropy in the system, demon, and the ancilla, showing the influence of coherence and entanglement on the result. A quantum implementation of Maxwell＇s demon adds more controllability to this paradoxical thermal machine and may find applications in quantum thermodynamics involving microscopic systems.

Characterization of barrier-tunable radio-frequency-SQUID for Maxwell's demon experiment

We present the design, fabrication, and characterization of a barrier-tunable superconducting quantum interference device（SQUID） qubit for the study of Maxwell＇s demon experiment. In this work, a compound Josephson junction（CJJ）radio-frequency（RF）-SQUID qubit with an overdamped resistively shunted direct-current（DC）-SQUID magnetometer is used to continuously monitor the state of the qubit. The circuit is successfully fabricated with the standard Nb/Al-Al Ox/Nb trilayer process of our laboratory and characterized in a low noise measurement system, which is capable of measuring coherent dynamics of superconducting qubits, in an Oxford dilution refrigerator. All circuit parameters are determined accurately by fitting experimental data to theoretical analysis and simulation, which allows us to make a quantitative comparison between the results of the experiment and theory.