Quantum Tunneling on Your Kitchen Table

To understand Quantum Tunneling we must bridge the intuitive gap between TV fantasies and existing Quantum Tunnel devices. In TV fantasies, actors flit about among universes with the aid of spectacular video special effects. With tunnel diodes you must take on faith that the meter readings are explained by quantum tunneling of invisible electrons across a microscopic barrier. In this Homegrown Quantum Tunnel experiment, the Quantum Barrier is big enough to see (more than a inch wide), and made of household materials.

Quantum Tunneling is a bizarre prediction of Quantum Physics, the physics which superceeded the physics of Einstein. Quantum Physics predicts there is a chance that a particle trapped behind a barrier without the energy to overcome the barrier may at times appear on the other side of the barrier without overcoming it or breaking it down. For example, assume youre in jail. It does not violate the laws of classical physics for you to exist inside your cell or outside your cell, but you do not have enough energy to penetrate or break down the walls. According to quantum physics, there is a certain probability you could disappear from the inside and reappear on the outside leaving the wall unbroken. Quantum Tunneling in this example is possible but highly unlikely.

In this experiment we will use giant photons travelling in paraffin to tunnel under a barrier of air. The probability of a photon tunneling is inversely proportional to the thickness of the barrier in terms of the photon's wavelength. To make the barrier big enough to see, we will use microwave photons with a large wavelength. At 10 GHz, photons are about an inch in size, so they can tunnel under a gap big enough for your hand to fit into. The barrier is the interface between the paraffin and the air, which the photons will be unable to cross until the conditions for Quantum Tunneling are established.

Ingredients:

• Two large paraffin prisms, 45^o angle.
• One Gunnplexer Generator, ( working transmitter ), and power source
• Two Gunnplexer Detectors, ( working detectors ) .
• Two current meters, typical range 1 mA or less.

Procedure:

Set up the experiment on an open nonmetallic surface.

Connect power to Generator (Gunnplexer transmitter). Connect meters to Detectors.

Check operation of the gunnplexers by setting the detectors about 1 or 2 m in front of the Generator.You should easily observe similar detector current in both detectors.

Set up the Gunnplexer Generator and two detectors as shown. Typical distance is about 1 or 2 meters.

Now interpose the two wax prisms as shown, with the diagonal faces far apart. Microwave photons pass into the front of the prism, but are unable to pass outside the diagonal back surface, so they undergo total internal reflection and pass out the side face.

According to classical physics, the zone behind the diagonal face is forbidden to the photons.

When the second prism is brought close to the first, the forbidden zone ( the Quantum Barrier ) becomes thin. Photons may appear in the second block where boundary conditions allow them again to exist and propagate onward without violating tha laws of classicl physics.

Tips:

Actually when I first did this in 1984 or so, I used a reflex klystron to produce the photons, just because I happened to have one handy. These days, Gunnplexers are much more available and easier to operate.