# Entanglement right where we can see it

The quantum phenomenon of entanglement (where two discrete objects are in perfect and instantaneous sync with each other) is something that is relatively easy to observe in microscopic and low energy states. But add in a little thermal energy or increase a system’s rest energy and then “boom!” the delicate linkage of entanglement gets smeared out by the macroscopic behavior of the system.

So the idea suggested in a paper published in Physics Review (a premiere journal) that suggests there might be a way around this, so that we could observe entanglement in the macroscopic regime is a big deal:

“In their new paper, Fernando Galve, from the University of the Balearic Islands in Spain, and his colleagues, suggest a way to overcome this environmental disturbance, or ‘decoherence,’ which threatens entangled states. They imagine the two oscillator blocks connected to each other with a third spring whose stiffness oscillates with time and thereby drives oscillations in the blocks. The team calculated that this driving force would continually put the two oscillators into just the right combination of states to generate entanglement and to compensate for decoherence.

The key is that the oscillators would be driven into a so-called squeezed state. Heisenberg’s uncertainty principle says that the product of the uncertainties in two complementary quantities (like position and momentum) must exceed a certain amount. In a squeezed state, the uncertainty in one of the quantities is squeezed down to a very small value, leaving all the uncertainty in the other quantity. For the coupled oscillators, the two quantities are the sum of and the difference between the two block positions. The squeezed state has most of the uncertainty in the sum, so the difference is known very precisely. If the position of one block is measured, the position of the other is instantly known to high precision–the signature of entanglement. The driving spring would keep pushing the oscillators into this entangled, squeezed state and counter the tendency for thermal energy to destroy it.

Galve and his colleagues think that if two ions placed in electromagnetic traps are coupled together with a capacitor connecting the traps, and the voltage in the traps is allowed to oscillate, entanglement could be achieved in an environment up to 50 degrees Kelvin. Nanomechanical resonators, which resemble small diving boards or vibrating drums, could also be coupled capacitively. The team believes that they could be entangled at about one degree Kelvin, rather than thousandths of a degree Kelvin, as others have assumed.”

Why is this interesting? Because there’s a deep question about how best to apply the craziness of the physics of the quantum regime to the macroscopic realm in which we actually live.

Do we live in a binary world? I’ve argued again and again that we don’t actually. We just choose to believe we do because it makes reality around us easier to understand. (This is because two-state logic is easier to manipulate than tri-state or higher-state logic.) The idea that we live in a binary logical universe leads us directly to a sense of absolute determinism, precludes middle or possible states, and shows up in present religious dialog as a deep desire for “Clarity”.

In the quantum world, there’s none of this. To make quantum mechanics work we pretty much have to give up determinism and accept probability. The thing is that while this is necessary in the microscopic regime, it’s not at all clear how we connect this with the classical, or macroscopic regime in which we live. People occasionally get a little overenthusiastic about applying the weirdness of quantum mechanics to the everyday human world. (I’ve done this on occasion.) The question that I’m currently deeply interested in is where the appropriate boundary between the micro and macro regime is to be found. It’s not at all obvious to me where that is. (Things like solid state electronics are based on micro quantum phenomenon yet they control macroscopic classical entities.)

This experiment, if it is successfully done, would have the effect of pushing that boundary a little more to the macro side of the field. And that’s worth looking at. Because if we determine that there are significant macroscopic implications to the non-deterministic regime of the microscopic, then there’s going to be a much stronger impetus to see what will need patching up in the classical manner in which we’ve done scholastic school systematic theology.

(Imagine what we’d say to Gustav Aulen for instance regarding his life-long task of creating a scientific and formal theology if it turned out that he was building on the wrong logical construct.)

When I get a chance, I’m thinking that the experience of transitioning a mathematical model of physical phenomenon from 2d to 3d (and the way that can sometimes give rise to completely unexpected properties) might be instructive in this situation. At least I want to have a good think about that this Fall.

## Author: Nick Knisely

Episcopal bishop, dad, astronomer, erstwhile dancer...