Heat from the void: how to catch the Unruh effect ⚡ экспресс
Detecting the Unruh effect for massive fields is complicated by strong suppression. An exponential suppression law has been obtained for the first time: the probability of field excitation is proportional to the exponential of minus the ratio of the particle's rest energy to the acceleration energy. Calculations in two models — the Unruh–DeWitt detector and quantum electrodynamics in a resonator — confirmed universality. For an electron at realistic accelerations of ~10²⁰ m/s², the suppression exceeds 10^9 orders of magnitude. Overcoming this requires that the rest energy be no greater than the acceleration energy; for the electron field, accelerations above 4.6×10²⁹ m/s² are needed, which are experimentally unattainable. A strategy is proposed to create a small effective mass in a laboratory system. Implementation: a superconducting qubit with a Josephson junction (analogue of the detector) and a microwave resonator (analogue of the scalar field). The optimal condition is that the product of the qubit current and the magnetic flux amplitude must greatly exceed the tunnel gap. The approach opens up an experimental perspective for an effect previously considered unobservable.
The void is deceptive. William Unruh showed that an accelerating observer perceives the vacuum as hot. The effect resembles the particle birth near black holes, predicted by Stephen Hawking, but instead of spacetime curvature, acceleration is at work. Yet for massive particles — electrons, for example — the heat is suppressed: it's like trying to hear the ring of a ship's hawser. Even at accelerations close to light speed, the signal is weakened by an unimaginable 10⁹ orders.
The solution: replace the detector with a super-light double. In a superconducting circuit, an 'effective mass' is created — an almost weightless ghost of a particle. It's like taking the thinnest guitar string: it responds to the slightest touch. Just so, the ghost particle under acceleration chisels thermal glow out of the vacuum, detectable by lab instruments.
An unexpected twist: the Unruh effect is the mathematical twin of Hawking radiation, but while the radiation of black holes is almost impossible to observe, this experiment turns quantum heat into something tangible. For the first time, we will be able to see how acceleration births entropy where previously there was only curvature.
🎯 The Unruh effect is mathematically almost identical to Hawking radiation, though one requires acceleration and the other a black hole's event horizon.
🎬 In Greg Egan's novel 'Incandescence', a civilization living in an accretion disk uses the Unruh effect to understand thermodynamics.