A couple of years ago, we looked at the possibility of using neutrinos to communicate with submarines.
The problem with underwater comms is that only the lowest frequency electromagnetic waves penetrate water to any depth and these are only capable of data rates of around 50 bits per second.
Neutrinos on the other hand pass more or less unhindered through anything. That makes them ideal for submarine communication, except for one thing. Neutrinos are somewhat reluctant to interact with matter and this makes them hard to measure. So any neutrino communications beam would have to be hugely powerful and any neutrino detector extremely big.
Nevertheless, neutrinos raise the possibility of communication at data rates some three orders of magnitude higher than is currently possible with submarines.
Today, a team at FermiLab in Batavia, Illinois, reveal that they have sent a digital message using a neutrino beam for the first time.
These guys used an experiment called NuMI (NeUtrino beam at the Main Injector) to generate an intense beam of neutrinos. The beam consisted of about 25 pulses each separated by 2 seconds or so, with each pulse containing some 10^13 neutrinos.
The beam is pointed at a detector called MINERvA weighing about 170 tonnes and sitting in an underground cavern about a kilometre away. To reach MINERvA, the beam has to travel through 240 metres of solid rock.
MINERvA is one of world’s most sensitive neutrino detectors and yet, out of 10^13 neutrinos in each pulse, it detects only about 0.8 of them on average.
Nevertheless, that’s enough to send a message. The FermiLab team used a simple on-off protocol to represent the 0s and 1s of digital code and transmitted the word “neutrino”.
The entire message took about 140 minutes to send at a data rate that these guys later worked out to be about 0.1 bits per second with an error rate of less than 1 per cent.
That’s not quite the three order of magnitude improvement submariners have been hoping for but at least it’s a proof-of-principle. “This result illustrates the feasibility, but also shows the signiﬁcant improvements in neutrino beams and detectors required for practical applications,” say the team.
Better results ought to be possible with more intense beams and larger detectors, such as the IceCube detector at the South Pole which uses the Antarctic icepack as a detector.
And submarine communication is not the only potential use. The FermiLab team mention various other alternatives such as interstellar communication and communication with spacecraft hidden on the far side of distant planets.
If that ever comes to pass, this experiment will be the equivalent of Alexander Graham Bell’s famous first telephone call in 1876, which consisted of the message: “Watson, come here. i want you”. By 1880, just four years later, there were some 60,000 telephone sets in the US.
Neutrino communication may take a little longer to catch on. On the other hand, if there’s anything in the faster-than-the-speed-of-light result from the OPERA neutrino experiment at last year, who knows what could happen.
Ref: arxiv.org/abs/1203.2847: Demonstration of Communication using Neutrinos