Forward wrote another paper, about his "Casimir battery": http://prola.aps.org/abstract/PRB/v30/i4/p1700_1 Federico Capasso (a friend of mine, but 35 years ago!) is also working in the field (at Bell labs now?). http://arxiv.org/abs/quant-ph/0109046 http://www.arxiv.org/abs/quant-ph/0410136 http://www.arxiv.org/abs/quant-ph/0312043