The vacuum of space is a chaotic sea of  quantum fluctuations.

Some have said that this vacuum energy can be harvested  to build our future starship engines, or manipulated to build warp drives.

It can't.

But it is technically possible to move real energy through the quantum vacuum without it  passing through intervening space.

Quantum energy teleportation may be as close as we get  to transporter beams.

But how close is that?

The laws of physics are pretty clear about a few  things.

Energy can’t be created out of nothing.

Nor can energy or matter or even information  travel faster than light.

The universe is very strict about enforcing these rules, but it also  seems pretty cool about us exploiting loopholes.

For example, it turns out it's OK to draw energy  from the vacuum of space as long as we put energy into the vacuum somewhere else.

And it’s also fine  for that energy to transfer between two distant places without traveling the intervening space  as long as something travels the same distance in its stead.

The protocol which makes this  possible goes by the name Quantum Energy Teleportation, or QET for short, and scientists  have confirmed this bizarre effect in experiments.

But before we get to that we have some  theory to learn.

We have to learn about quantum entanglement, quantum teleportation,  and the quantum vacuum before we can do quantum energy teleportation.

This’ll just take a  few minutes with some help from favourite theoretical physicists, or should I say  hypothetical physicists, Alice and Bob.

We start in Bob’s lab where he’s made a pair of  entangled qubits, A and B, also known as a Bell pair.

In this case the quantum information in  the qubits takes the form of the direction of the quantum spin—up or down.

For this Bell pair,  the spin for each particle is undefined—it’s a quantum superposition of both up and down.

The  only thing that’s really known about the spins of A and B are that they are opposite.

So Alice  stops by to pick up qubit A and then goes back to her lab and measures its spin.

Let’s say she  measures up.

Because this is an entangled pair, qubit B has no choice but to take on the value of  down.

In other words, the wavefunction of the Bell pair collapses from up-down AND down-up to just  up-down.

Alice calls Bob and tells him that he has a down qubit and he confirms with a measurement.

That’s a cute trick, but it would work equally well if the spin of the particles were fixed from  the beginning.

This gets more interesting if Alice chooses different directions for  her measurement—for example, measuring left-right will ensure a left or right spin, and  Bob’s will still be opposite but on a different axis.

This is a real superluminal or non-local  influence, and in general this sort of experiment is called a Bell test.

We’ve covered it before.

Although there are correlations between Alice’s choice of measurement axis and Bob’s readouts,  it’s still not possible to send information faster than light this way.

Those correlations  can only be seen when Alice communicates to Bob her measurement outputs or axis choices.

Still, it’s weird—spookily weird according to Einstein.

There are ways to make entanglement  weirder however.

For example, Alice could take her half of the Bell pair and have it interact with  a new, independent qubit in a way that causes Bob’s qubit to take on the quantum state of that  new qubit, meanwhile destroying the version held by Alice.

It’s as though the quantum state  of the new qubit is teleported.

But again, Bob can only access this quantum state after  receiving classical information about the interaction from Alice.

This is “regular” quantum  teleportation and it’s been achieved multiple times in experiments, with transfer of quantum  information achieved over hundreds of kilometers, and even between Earth’s surface and a satellite.

Moving information around is nice, and actually useful for things like quantum computers and the  quantum internet.

But what about moving actual stuff?

We’re a long way off teleporting  actual matter with transporter beams, but matter is made of energy, so let’s start by  trying to move energy around.

To do that we’ll need to expand the thought experiment a bit.

This time we’ll give Alice and Bob 10 Bell pairs.

If Alice measures the spin of all  10, she’ll know the spin of all 10 of Bob’s, assuming he uses the same up-down measurement  direction.

Let’s add one more feature.

We’ll say the qubits are all suspended in a  magnetic field so that the spin up state is slightly lower energy than the spin down state.

In the process of measuring the spin, Bob needs to either add energy into the system  for the low energy spin-up states or extracts the same amount of energy for the high-energy  spin down states.

Because he doesn’t know which will be up and which down, if he measures  all 10 he’ll end up with a net zero energy.

But what if Alice does her measurements first, and  is able to tell Bob exactly which qubits are up and which are down?

Then Bob can safely measure  only the qubits that will allow him to extract energy from the system.

Alice will always have  spent more energy making the measurements than Bob can extract, so energy conservation  isn’t broken.

But it certainly does feel like Alice teleported her spent energy to Bob.

This all sounds a bit impractical.

For example, before they can teleport energy they need to  physically exchange prepared qubits.

That’s where the quantum vacuum will finally come back into it.

As a reminder, the vacuum in quantum mechanics is not the passive nothingness of classical  physics.

Every point in space is permeated by quantum fields, whose excitations give us the  particles and forces.

The lowest energy state of these fields is typically zero, which means  no particles—a perfect vacuum.

But due to the Heisenberg uncertainty principle, quantum  systems can’t take on perfectly defined values.

So the zero energy state is only  approximately zero.

It’s zero on average, but when you make a measurement at a given spot  it might be a bit larger or smaller than zero, and the fluctuations witnessed by an individual  series of measurements seem completely random.

Let’s try an analogy.

Imagine a  pond.

There’s a very light rain, so that at any time the surface of the pond is a  pattern of overlapping ripples.

The height of the ripple at any one point is subtly correlated with  the entire ripple pattern.

You add a device to track the ripple height at one point.

On its own,  it seems to fluctuate randomly.

But measuring at two different spots you’ll see correlations due to  the fact that you’re measuring correlated ripples.

In principle, you could even extract energy  from random-seeming up-down motion by using the knowledge you gain about the global ripple  pattern.

Not only that, but your measurement itself causes ripples, which influences the  measurements you make elsewhere on the pond.

The quantum vacuum is a bit like the surface  of our pond, but now all oscillations at all frequencies—both positive and negative—are  simultaneously present but balanced in such a way that the pond—the vacuum—looks still or  empty.

But when you look close you can’t help but interact with the vacuum, and suddenly  the wild fluctuations can become apparent.

And just like the pond surface, fluctuations at  one point are correlated with all other points.

Each point is entangled with every other point  in the true quantum sense.

So, while measurements of the quantum vacuum at any one point yield  random energies that average to zero, those same quantum fluctuations are correlated with the  fluctuations measured at any other spot, even if the spots are separated by large distances.

So the idea of quantum energy teleportation is that this quantum entanglement can be used  to extract energy from one location based on measurements made at a completely different  location.

It’s the same idea as our energy extraction from particle spins, except this  time we don’t pre-prepare entangled pairs, instead we use the preexisting  entanglement in the vacuum itself.

The process of extracting entanglement from the  quantum vacuum is called entanglement harvesting.

This is an interesting topic all on its own—it  suggests that two measurement devices can become entangled just by measuring spatially separated  but entangled regions of the quantum vacuum.

This entanglement should be able to be used as  a resource for teleportation-like protocols.

And so in 2008, physicist Masahiro  Hotta proposed the protocol of Quantum Energy Teleportation.

Here’s  a crude idea of how it works.

Let’s say Bob now wants to extract free energy  from the quantum vacuum.

Because he’s actually studied physics, he knows that this is impossible  on its own.

So, once again, Bob calls Alice.

This time Alice doesn’t even have to travel  to Bob to collect an entangled particle.

The quantum vacuum at her location is  already entangled with the vacuum at Bob.

She can make a measurement and  send the results of that measurement to Bob by classical channels and Bob can use  that information to extract real energy.

Let’s look at what the quantum fields are actually  doing in the QET protocol.

As I mentioned earlier, we can think of the quantum vacuum as being  made up of every possible frequency mode, which together cancel each other out to yield the  apparent emptiness—zero average energy—observed on large scales.

But this balance can be disturbed.

It’s disturbed by black holes to produce positive energy outside the black hole and negative  within—that’s Hawking radiation, and it’s disturbed by the measurements made by Alice and  Bob.

Alice’s measurement yields a positive energy, and that means she has injected energy into  the vacuum.

She disturbed the vacuum so the underlying vibrational modes no longer cancel,  but rather yield an excited state.

Bob then uses the information from Alice’s measur 1ement  to tune his own measurement, which ensures he sees the vibrational modes that were depleted  to power Alice’s excitation.

Bob sees a negative energy density in the vacuum, and finds that the  missing energy is now in his measuring device.

Alice needs to input at least as much energy  as Bob extracts.

That’s why this protocol feels like energy teleportation—energy injected  into the quantum vacuum at one location is extracted at a different location without  it ever taking the form of real particles.

It doesn't violate energy conservation.

It  also doesn't  violates relativity.

Because the measurement information Alice sends to  Bob still has to travel by classical channels.

This idea of extracting energy from  a seemingly random, chaotic system by using detailed information about the system  is not new.

It’s the same idea as Maxwell’s demon.

In this thought experiment, we start  with a gas at a uniform temperature.

Energy can’t be extracted from it because it’s already in  equilibrium.

But we introduce an agent—Maxwell’s demon—who carefully monitors the trajectories  of particles and sorts the particles according to temperature.

This produces a temperature  gradient, so work can now be extracted from the gas.

It seems like we got energy out of  thin air, but really the demon had to expend energy to do the computations to sort the gas—and  expends at least as much energy as was extracted.

Just like Alice had to expend energy to  “sort” the quantum vacuum for Bob.

The difference with quantum energy teleportation is  it’s not possible to directly monitor the local vacuum and then extract energy from it—that  local activity puts more energy into the vacuum than can be extracted.

That’s what’s  cool about quantum energy teleportation—it’s a way to “Maxwell’s demon” the vacuum itself  from a remote location so it can be harvested.

So, is quantum energy teleportation even possible?

The answer seems to be yes, although not yet via the vacuum.

It was first demonstrated in 2022  by a team of physicists primarily based out of the Institute for Quantum Computing (IQC) in  Waterloo Canada.

They used entangled qubits in the form of the quantum spin of carbon atoms in  a molecule of transcrotonic acid—more commonly used to create paints and glue.

The qubits were  stabilized and manipulated using nuclear magnetic resonance—the same physical phenomena which  allows MRI machines to work.

A pair of entangled qubits in their lowest energy states were used as  proxies for the quantum vacuum and a third qubit to mediate the measurement.

The team found that  the correct measurement process enabled energy to be deposited in one qubit and then extracted  from its entangled partner despite the latter being in the lowest energy state, so in principle  having no energy to give.

This energy transfer occurred much more quickly than it would normally take energy to travel naturally in this system.

This successful demonstration of quantum  energy teleportation was quickly followed up by an independent experiment in 2023 using  IBM’s superconducting quantum computer, confirming that QET seems to be  possible in realistic lab settings.

The amount of energy transferred  in these experiments is very small.

The same will be true if we ever manage to do  this via vacuum entanglement.

The latter will also have a very limited range.

But this  could still be useful in quantum computers and various nanodevices.

But beyond moving  energy around, QET experiments might be even more valuable for understanding the nature  of entanglement and the quantum vacuum.

Remember that QET in the quantum vacuum  leads to a negative energy density.

This is the type of energy density required in  general relativity to produce exotic effects like wormholes and warp drives.

We’ve known for some  time that negative energy densities are possible, for example in the Casimir effect where  certain vibrational modes are excluded from the space between parallel conducting plates.

But the Casimir effect requires the presence of these plates, which more than cancel out the  effect of the negative energy between them.

But the cool thing about the QET negative energy  density is that it can be generated remotely, which in principle may mean that  its effect on spacetime curvature can be studied.

And almost certainly will  prove to be useless for faster than light motion or the inevitable capacity for time  travel that results from FTL.

The universe seems to be generous only with loopholes  that do NOT violate relativity this way.

But quantum energy teleportation could give  us a very new understanding of the connection between negative energy, vacuum entanglement,  and the curvature and even fabric of spacetime.