My father used to tell me, “Believe nothing you hear and only half of what you see.” When dealing with quantum mechanics you may want to revise that statement to say “believe nothing you see”. Because when dealing with the quantum world, one would be well served to forget what you see everyday and accept what you can’t see on good faith. Einstein himself had problems accepting quantum mechanics even though he was partially responsible for its beginning. Anyone who can look at quantum theory and not have their scientific mind spooked does not fully understand it.
When dealing with the subatomic world, the physical rules and laws that govern our world or the “classical” world do not apply. What we know about our surroundings from mass to gravity is nearly useless when it comes to the very small. Classical physics encompasses things like motion of planetary bodies and gravity. Quantum physics deals in particles such as protons, neutrons, electrons and photons. There are several properties of quantum physics that flat out make no sense in classical terms. One such property is that of quantum entanglement.
Quantum entanglement is something that is being studied at the very forefront of particle physics. There is much hope for what quantum entanglement can provide technology if fully understood. Quantum computers and cryptography is the first idea and project being worked. Quantum entanglement is described by scientists as “spooky.” To understand quantum entanglement, we should first take a quick trip down a spooky road.
Behavior of particles on the subatomic level defies how we think of matter. Matter in the classical sense exhibits certain capabilities and limitations. Subatomic particles fly in the face of those limitations and do such things as pass directly through solid matter and emerge on the other side. Quantum particles can occupy two physical positions in a given space at the same time. Have you ever wished you could occupy two places at once? Quantum particles can communicate over vast distances at incredible rates. Photons can even behave as both a wave and a particle at the same time. How does this happen? I don’t know either but it does. Scientists don’t exactly know but they are working the issue.
The first spooky property that applies to entanglement is called superposition. A superposition is the way that a particle can occupy two places at once. This action occurs when a specific particle is traveling along without anyone looking. Once we attempt to measure the particle, or look at it, we disrupt its quantum state and force the particle to make a choice. Any quantum state is affected by our measurement and will disrupt its superposition. When we measure a quantum field, we must shine light on it or a laser or something to be able to see it. When the photons from the light or the laser, just as an example, hit the particle we are attempting to view the energy level is changed and thus the state is changed. Electrons absorb photons and they change energy levels, altering the original state. So anytime we look, the particles change from their original state.
So say for example we have a measuring device for atoms. This device looks like a long tube. There is a single opening and a single exit but in the middle the tube forks and has two separate paths to take. The two paths then meet again to form the single exit. In the forked paths we place a device to detect when a particle passes by. If we shoot a particle down the tube and we do not look the particle has an equal chance of traveling down the left side of the tube, the right side of the tube and both at once. This is the basis of Erwin Schrodinger’s cat paradox. Now, when we turn on our particle detector in the middle of the journey, the particle will instantly choose which state it wants to occupy. Light exhibits the same behavior in the wave-particle duality property of light. So a superposition is a combination of all the possibilities of states of a given particle. A superposition can be disturbed by any interference. This is exactly the property that is enticing to those questing for quantum computers.
When two particles are entangled, or perhaps more than two, they are in a superposition of each other. This means that as long as both particles go undisturbed, they will exist independent of each other in their original state. Once one is disturbed, the other is also disturbed no matter their location. This was the idea behind the thought experiment, the EPR experiment. Here, Einstein and company proposed that two particles could be entangled millions of light-years apart. One particle becomes disturbed and the other particle, being millions of light-years away, would also become disturbed. This infers that some type of information is being passed faster than the speed of light. So with that in mind, scientists believe they can encode information in the form of qubits and use them to transmit information.
Conventional computers use binary code or 1’s and 0’s and yes or no answers to encode their information. They only use 1’s and 0’s because using more numbers would only slow down the computing process. Quantum computers would be able to carry more qubits and process them faster. They would also be very much more secure using quantum cryptography.
When qubits would be transmitted, they would be transmitted in a superposition. If any would-be hacker tried to intercept the message, the superposition would break down and with it the qubits and the message. This would be the ultimate form of encryption.
Quantum computer and encryption technology is still years away because of the elusive nature of the quantum world. Great strides are being made in the right direction and soon we will be able to shift our technological focus toward the quantum. The quantum world has much to offer us and we will begin to decode it further to harness all it has to offer.