Single atom heat engine as a sensitive thermal probe.

A single atom heat engine has a sensitive thermal probe preparation and manipulation of quantum systems for the design of new technology require the ability to detect the influence of physical properties of the environment with high precision however many of the variables cannot be measured directly as they are not proper quantum observable and must be instead inferred from indirect measurements the temperature of the system is such a property on the other hand the emerging fields of thermodynamics in the quantum regime sheds new light on energy exchange processes between interactive. Small quantum systems under environment manipulating these interactions in a structural manner reveals simple laws that relates property of the environment to observable of the quantum system.

For example.

The power output of a depends on the temperature difference of the bath using this concept we design a temperature sensor to understand the working principle of here we see the water wheel that spins due to the river flow in this sense we can consider the river as an engine that produce work. Thanks to the water gradient this output work is employed to move a wheel in our quantum model the engine and the wheel are replaced by a trapped ion.

 Radial degree

Its radial degree of freedom acts as an engine the output work is provided by the temperature gradient produced by two separated thermal baths that interact with the ion when this is moved to these locations leading to an engine cycle on the other hand this output work is transferred to the axial degrees of freedom that mimics the wheel and make the ion oscillate in this direction due to the coupling nature between the ion and the baths the oscillations grow linearly Every time the engine performs a cycle.

The cycling nature

The cycling nature of the engine allows transforming the small bath-temperature differences into macroscopic oscillations of the flywheel in an inverse perspective measuring these oscillations allows us to use this engine as a sensitive thermometer as the generated output depends on the relative temperature differences if one of the bath is known then other is fully determined

The working principle of our model

Once we have explained the working principle of our model now let's move to the lab for the experimental details this project started 2016 when we did the smallest heat engine with a single ion now this project is funded by the research unit thermal machines in the quantum world and the details are following in this lab we are running a single atom heat engine our system is a single calcium ion trapped in a linear Paul trap we did a modification to the power trap so that our radio frequency electrode are tilted to the symmetry axis of the trap by a small angle and this tilt induces a small coupling between the radial state and the actual motion of the ion the working principle of the heat engine is thus simple depends on the temperature of the radial state the ion experiences a different displacement force in the actual direction so if we periodically switch the temperature of the radial state we excite a coherent motion in the axial direction which serves as the energy output of the engine the cold path is implemented by applying Doppler cooling to the iron and a hot bath is employed by applying noise as well on the DC compensation electrodes then the engine is run for a number of cycles and after this by simply taking a picture for a brief period of time we can estimate the position of the ion and therefore determine the growth of the amplitude and therefore determine the temperature difference.

Heat engine vs Heat pump

We are going to compare Heat engine, Heat pump and Refrigerator on basis of efficiency and coefficient of performance we also derive equation of Conform heat pump and refrigerator.

Here heat engine is used to perform work. Where heat pump is used for heating purpose in cold region and refrigerator is used for cooling purpose in hot region In heat engine

Question about heat engine

Q1 amount of heat is added to the system that is we burn fuel in heat engine to produce thermal energy to perform some useful work which is net work done by the engine.

Q2 amount of heat is rejected. That is heat of exhaust gases out of engine cylinder so to calculate efficiency of engine.

Here we have the formula that is output upon input so here output is net work done and input is heat added to engine therefore the formula is Q1 minus Q2 upon Q1 and here Q1, Q1 get canceled, and we will get efficiency of engine as none minus Q2 by Q1.

In case of refrigerator

we extract heat from cold region and maintain cold region to low temperature because the purpose of refrigerator is to cool the system therefore here we provide work by means of compressor here the COP that is coefficient of performance is the ratio of heating effect or cooling effect to the work input in refrigerator cooling effect is Q1 that is we extract Q1 amount of heat from cold region and reject Q2 amount of heat to hot region so difference of Q2 minus Q1 is work input and here work input is compressor work therefore COP for refrigerator is equal to cooling effect that is Q1 upon work inputnwhich is Q2 minus Q1

Heat Pump

Now heat pump is the device here we take out heat from cold body which is Q1 and deliver heat to the hot body the delivered heat is Q2 therefore COP of heat pump is the amount of heat is rejected that is Q2 upon net work done which is Q2 minus Q1 now here we have to derive the equation that is COP for pump is equal to one plus COP for refrigerator and here is the formula of COP for refrigerator is Q1 by Q2 minus Q1 minus Q1 plus Q1 get canceled, and we will get the formula of COP for heat pump that is Q2 minus Q1 in this way we prove that COP of heat pump is greater than one

 

How to make a project with heat engine

Here's a neat heat engine made using material from a coffee bag, and that sort of opens and closes like a flower. The petals of the rotating part are strips cut from the coffee bag. Behind it on one side is a glass of hot water, meaning the air around is it hot, and on the other side is a glass of cold water, with cold air surrounding it. You can see the petals straighten out in the hot air, .and curl back up in the cold air, making it an unbalanced wheel that keeps on rotating. It's pretty simple to make and in this video I'll show you how.For the stator, I've made this stand with scrap wood. And two stiff scrap aluminum bars. In this bar I've made a tiny indentation near the top. I attach some neodymium magnets to one bar, and tape some more to the other bar For the rotor, I've cut this round plastic disk, and stick a needle through it.

 

Next step

By putting the sharp end of the needle in the tiny indentation, and with the help of the magnetic fields, the needle just sits there, and turns very easily. But, the disk is unbalanced, always coming to a stop with the same side down. So I sand away some plastic from that side. It still isn't balanced, so I sand some more, .until finally the rotor stays pretty much however I orient it. Then I start cutting up the coffee bag, and cut a strip from it. The strip is 1/2" wide by 2 1/8" long. A piece of duct tape holds it onto the disk. Then I attach another piece and make sure they both stretch out the same distance from the center.

 

Next

But notice that one petal always hangs down, so the whole thing is unbalanced. After trimming a little from the petal that was hanging down, the rotor balances better now. I give the petals a little curvature using the blunt edge of a pair of scissors.I then put out two glasses of water, one hot and one cold, along with the stand and the heat engine's rotor. From the top you can see this petal straightening out in the hot air surrounding the glass containing hot water, and this petal curling up in the cold air surrounding the glass containing cold water.

 

Heat engine project

Eventually I add all eight petals. But notice that since it's now heavier I've also had to add more magnets. And as you'd expect the rotor is unbalanced again, with the same side always hanging down. To fix it this time I add a little extra tape on the opposite side. And now it stays put wherever I leave it. It's balanced. After using the scissors again to give all the petals a curvature,I give it a try. All that careful measuring and balancing has. Paid off as it works the first time. You can see the petals straighten out on the hot side, and curl up again on the cold side.