Sharpening accepted thermodynamic wisdom via quantum control: or cooling to an internal temperature of zero by external coherent control fields without spontaneous emission

Abstract

Cooling of internal atomic and molecular states via optical pumping and laser cooling of the atomic velocity distribution, rely on spontaneous emission. The outstanding success of such examples, taken together with general arguments, has led to the widely held notion that radiative cooling requires spontaneous emission. We here show by speci®c examples and direct calculation, based primarily on breaking emission±absorption symmetry as in lasing without inversion, that cooling of internal states by external coherent control ®elds is possible. We also show that such coherent schemes allow us to practically reach absolute zero in a ®nite number of steps, in contrast to some statements of the third law of thermodynamics.

Time Evolution of a Modified Feynman Ratchet with Velocity-Dependent Fluctuations and the Second Law of Thermodynamics

“…Note that these maxima lie in the diminishing-oscillatory regime, as per the second paragraph of this Sect. 4, and hence are larger [by a factor of 2(1 − e −1 )]t h a n (19) and (25)] -but smaller (by a factor of 2/e) than the absolute maxima as per (30). [Similar results…”

“…But any "practical" time evolution is limited to at most a large but finite number N of pawl-peg interactions. Hence, V N and P(V) N − 1 2 , and likewise V N and |P(V) N − P(V) mw |, attain "practical" maxima -corresponding to small but not infinitesimal 1 − (F + R − 1)= ⇒ small but not infinitesimal A and to large but not infinite N -thatarealmostbutnotquiteaslarge as the absolute maxima given in (30) and (31) …”

“…As an aside, note that the DP's Carnot-engine [17] power outputs, are maximized (at θ = 0) if the Markovian time evolution of our DP is allowed to approach as closely as is "practical" (as per the fifth paragraph of this Sect. 4) to its final steady state, with A −→ 0andN −→ ∞ as per the first sentence of the paragraph containing (30) and (31) [17], corresponding (as closely as "practical") to the absolute maxima given by (30) and (31). Maximizing P * with respect to N at given fixed F + R − 1 =⇒ given fixed A, by setting…”

“…Perhaps, in passing, it might be noted that there have also been challenges -albeit unrelated to this present chapter -to the first [29] and third [30] laws of thermodynamics.…”

Absolute Zero and Even Colder?

“…3, we consider CSRR via positional isolation, by means of weighing or Stern-Gerlach apparatus, of entities that happen to be in their ground states, with reference to a specific one of the quantum-control-refrigeration (QCR) methods investigated in Ref. [1], but we will not employ this or any other QCR method per se.…”