Keghairahan Mencari Duit Sampingan

Dalam kehidupan masakini yang tertekan dengan kedudukan ekonomi yang kurang mantap, ramai muslim mencari alternatif tambahan dengan menjalankan pendapatan sampingan seperti melabur, menjadi pemilik modal sesebuah syarikat, perlaburan emas, MLM, online cash dan sebagainya. Kita semua akur bahawa tuntutan serta keperluan hidup zaman kini amat tinggi sejajar dengan perkembangan teknologi dan ilmu yang baru. Namun, adakah kita sebagai seorang muslim pernah memikirkan, meneliti, menyiasat adakah sumber pendapatan sampingan ini benar-benar halal dan sah disisi islam?

sebagai seorang muslim, wajib untuk kita memastikan bahawa sumber kewangan yang masuk ke dalam keluarga kita adalah dari sumber yang sah. Gaji yang diperolehi juga perlulah dipastikan bersih dan suci tanpa unsur syak. Kita selalu berusaha memastikan kerja makan gaji kita agar sentiasa mengikut etika seperti tidak ponteng kerja, melakukan tugasan dengan sempurna, mengeluarkan zakat pendapatan dan sebagainya agar hasil titik peluh yang diperolehi adalah bersih namun kita selalu terlupa memastikan sumber sampingan ini juga dari sumber yang bersih dan suci lagi menyucikan. Setelah meneliti tulisan Ustaz Zaharuddin Abd. Rahman, dapat disimpulkan bahawa, mencari rezeki yang halal adalah penting dan perlu penelitian.

Ada syarikat yang sangat popular baru-baru ini menawarkan pakej pemilikan modal yang menjanjikan keuntungan tetap setiap 3-4 bulan dan ramai yang terpedaya dengan pulangan yang menguntungkan tanpa memastikan halal atau haram kaedah yang digunakannya. (keterangan lanjut di http://www.zaharuddin.net/pelaburan-&-perniagaan/260-pelaburan-masa-lepas-a-jaminan-untung.html)

Begitu juga perlaburan emas, yang semakin menjadi perhatian umum. Jual beli emas tidak haram, tetapi kaedah jual beli serta perlaburannya perlulah jelas mengikut hukum. (keterangan lanjut di http://www.zaharuddin.net/pelaburan-&-perniagaan/764-hukum-akaun-pelaburan-emas-di-bank-malaysia.html)

Bagi perniagaan MLM pula, kebersihan kaedahnya perlu diteliti agar tidak termakan sumber yang tidak bersih. (keterangan lanjut di http://www.zaharuddin.net/pelaburan-&-perniagaan/222-multi-level-marketing-menurut-shariah.html)

Semua muslim tahu bahawa 9 dari 10 sumber rezeki datang dari perniagaan dan ketahuilah bahawa, perniagaan memerlukan pengendalinya mendalami hukum hakam agama agar sumber betul-betul mengikut syariah yang ditetapkan. Namun kita dapati rata-rata rakyat Malaysia tidak cakna dengan hukum syariah dalam perniagaan dan lebih tertarik dengan pulangan yang menguntungkan tanpa menyiasat dahulu kaedah perniagaannya.

Begitu juga dengan rukun islam yang ke-4 iaitu mengeluarkan zakat bagi menyucikan sumber pendapatan. Rakyat Malaysia tahu tentang syahadah, sembahyang, puasa dan mengerjakan haji jika mampu namun persoalan zakat sering diambil mudah. Zakat pendapatan perlu dikeluarkan setiap tahun berdasarkan kiraan-kiraan tertentu kerana setiap hasil titik peluh kita ada sebahagiannya adalah hak milik org miskin, anak yatim dan golongan yang telah ditentukan. Andai kita tidak mengeluarkan zakat maka kita telah memakan bahagian yang bukan hak kita. Begitu juga dengan zakat simpanan, jika cukup haul (setahun) serta nisabnya, wajib kita mengeluarkan zakat. Beberapa zakat lain yang selalu diabaikan ialah zakat emas, zakat perniagaan dan sebagainya.

Islam adalah agama yang syumul dan segala peraturan yang ditetapkan adalah sangat indah dan bermanfaat untuk sejagat dan tidak tertumpu kepada satu-satu golongan sahaja. Hukum perniagaan dan zakat juga amat baik bagi mengukuhkan kewangan dan ekonomi islam.

Apabila satu syarikat milikan bumiputra dan muslim dikatakan haram, tidak betul atau tidak patuh syariah, muslim yang lain sering melemparkan kata-kata bahawa melayu ingin menjatuhkan sesama melayu, melayu tidak boleh melihat anak bangsa maju, melayu pantang melihat anak bangsa berjaya, melayu berhati busuk dan tidak senang dengan kemewahan bangsa sendiri dan dituduh sengaja melemparkan fitnah. Namun, adakah kita sesama melayu atau lebih tepat dikatakan muslim, sedar bahawa teguran dari sesama muslim itu adalah untuk kebaikannya juga? Apakah yang kita kejar selama ini? Kesenangan dan kemewahan hidup di dunia atau kebahagian yang kekal di akhirat?

Ultrathin alternative to silicon for future electronics

  Duplicate from physics.org.

November 22, 2010 Enlarge

Fabricating an indium oxide (InAs) device starts with a) epitaxially growing and etching InAs into nanoribbon arrays that are get stamped onto a silicon/silica (Si/SiO2 ) substrate; b) and c) InAs nanoribbon arrays on Si/SiO2; d) and e) InAs nanoribbon superstructures on Si/SiO2. 

Credit: courtesy of Ali Javey, UC Berkeley

There's good news in the search for the next generation of semiconductors. Researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California Berkeley, have successfully integrated ultra-thin layers of the semiconductor indium arsenide onto a silicon substrate to create a nanoscale transistor with excellent electronic properties. A member of the III–V family of semiconductors, indium arsenide offers several advantages as an alternative to silicon including superior electron mobility and velocity, which makes it an oustanding candidate for future low-power, high-speed electronic devices.

"We've shown a simple route for the heterogeneous integration of indium arsenide layers down to a thickness of 10 nanometers on silicon substrates," says Ali Javey, a faculty scientist in Berkeley Lab's Materials Sciences Division and a professor of electrical engineering and computer science at UC Berkeley, who led this research.

"The devices we subsequently fabricated were shown to operate near the projected performance limits of III-V devices with minimal leakage current. Our devices also exhibited superior performance in terms of current density and transconductance as compared to silicon transistors of similar dimensions."
For all its wondrous electronic properties, silicon has limitations that have prompted an intense search for alternative semiconductors to be used in future devices. Javey and his research group have focused on compound III–V semiconductors, which feature superb electron transport properties. The challenge has been to find a way of plugging these compound semiconductors into the well- established, low-cost processing technology used to produce today's silicon-based devices. Given the large lattice mismatch between silicon and III-V compound semiconductors, direct hetero-epitaxial growth of III-V on silicon substrates is challenging and complex, and often results in a high volume of defects.
"We've demonstrated what we are calling an 'XOI,' or compound semiconductor-on-insulator technology platform, that is parallel to today's 'SOI,' or silicon-on-insulator platform," says Javey. "Using an epitaxial transfer method, we transferred ultrathin layers of single-crystal indium- arsenide on silicon/silica substrates, then fabricated devices using conventional processing techniques in order to characterize the XOI material and device properties."

The results of this research have been published in the journal Nature, in a paper titled, "Ultrathin compound semiconductor on insulator layers for high-performance nanoscale transistors." Co-authoring the report with Javey were Hyunhyub Ko, Kuniharu Takei, Rehan Kapadia, Steven Chuang, Hui Fang, Paul Leu, Kartik Ganapathi, Elena Plis, Ha Sul Kim, Szu-Ying Chen, Morten Madsen, Alexandra Ford, Yu-Lun Chueh, Sanjay Krishna and Sayeef Salahuddin.

To make their XOI platforms, Javey and his collaborators grew single-crystal indium arsenide thin films (10 to 100 nanometers thick) on a preliminary source substrate then lithographically patterned the films into ordered arrays of nanoribbons. After being removed from the source substrate through a selective wet-etching of an underlying sacrificial layer, the nanoribbon arrays were transferred to the silicon/silica substrate via a stamping process.

Javey attributed the excellent electronic performance of the XOI transistors to the small dimensions of the active "X" layer and the critical role played by quantum confinement, which served to tune the material's band structure and transport properties. Although he and his group only used indium arsenide as their compound semiconductor, the technology should readily accommodate other compound III/V semiconductors as well.
"Future research on the scalability of our process for 8-inch and 12-inch wafer processing is needed," Javey said.

"Moving forward we believe that the XOI substrates can be obtained through a wafer bonding process, but our technique should make it possible to fabricate both p- and n- type transistors on the same chip for complementary electronics based on optimal III–V semiconductors.

"Furthermore, this concept can be used to directly integrate high performance photodiodes, lasers, and light emitting diodes on conventional silicon substrates. Uniquely, this technique could enable us to study the basic material properties of inorganic semiconductors when the thickness is scaled down to only a few atomic layers."

Provided by Lawrence Berkeley National Laboratory

Molecular spectra

When atom or molecule makes transition from a state of energy E1 to another state with energy E2, it absorbs or emits energy, where:

E2-E1=hv

For atoms, energy states are determined by arrangements of electron clouds (electronic states). Each line of spectrum observed corresponds to an electronic transition.

For molecules, the spectra are more complicated. Their states are not only depending on the electron cloud but also by the geometrical arrangement of the nuclei and their movements. This is because molecules have additional internal degree of freedom.

Molecules:

• possess more electronic states than atoms
• nuclei can vibrate around their equilibrium position 
• may rotate around axes through its center of mass.

For each electronic state, various vibrational and rotational energy levels are exist.

Molecular spectra can be categorized as below:
1) Transitions between different rotational levels for the same vibrational (and electronic) state lead to pure rotational spectra with wavelengths in the microwave region
2) Transitions between rotational levels in different vibrational levels of the same electronic state lead to vibration-rotation spectra in the mid-infrared
3) Transitions between two different electronic states have wavelengths from the UV to the near infrared. Each electronic transitions comprises many vibrational bands corresponding to transitions between the different vibrational levels of the two electronic states involved. Each of these bands contains many rotational lines with wavelengths or frequencies.

Source: Molecular Physics: Theoretical Principles and Experimental Methods by Wolfgang Demtroder

University Social Responsibilities Program-Physics Department, UMT

"Program Selangkah Kearah Kecemerlangan Fizik 2010" is a program organized by Kelab Kemahasiswaan Fizik, UMT (KEMAFIZ). The objectives of the program are to expose Form 3 students from selected local secondary school to Physics, to expose campus life to them, to introduce the beautiful of Physics and its miracles and at the same time to establish contact and relationship with the community.

The program is expected to be conducted annually and the participation involves most of the secondary school in the neighborhood. This is the first ever USR program organized by Jabatan Sains Fizik and has been fully supported by HEPA, UMT, JPNT and Terengganu Education Exco. The program has been reported by local press, Sinar Harian.

 

The Deputy Dean (Academic & Student's Affair), Prof Madya Dr. Aziz bin Ahmad, Head of Department, Dr. Mohd Ikmar Nizam Mohamad Isa, Physics Department's Lecturers, Schools' Representatives (Teachers), Physics Department Undergraduate and Postgraduate Students as an Organizing Committee and Participants (Form 3 students from five schools in neighborhood) are having picture together in Closing Ceremony in Kafe baru, UMT.

Quantum Phenomenon Observed: Atoms Form Organized Structure from Unorganized One

Duplicate from:http://www.sciencedaily.com/releases/2010/07/100728131711.htm

Quantum Phenomenon

ScienceDaily (July 29, 2010) — In an international first, physicists of the University of Innsbruck, Austria have experimentally observed a quantum phenomenon, where an arbitrarily weak perturbation causes atoms to build an organized structure from an initially unorganized one. The scientific team headed by Hanns-Christoph Nägerl has published a paper about quantum phase transitions in a one dimensional quantum lattice in the scientific journal Nature.

With a Bose-Einstein condensate of cesium atoms, scientists at the Institute for Experimental Physics of the University of Innsbruck have created one dimensional structures in an optical lattice of laser light. In these quantum lattices or wires the single atoms are aligned next to each other with laser light preventing them from breaking ranks. Delete using an external magnetic field allows the physicists to tune the interaction between the atoms with high precision and this set-up provides an ideal laboratory system for the investigation of basic physical phenomena. "Interaction effects are much more dramatic in low-dimensional systems than in three dimensional space," explains Hanns-Christoph Nägerl. Thus, these structures are of high interest for physicists. It is difficult to study quantum wires in condensed matter, whereas ultracold quantum gases provide a versatile tunable laboratory system. And these favorable experimental conditions open up new avenues to investigate novel fundamental phenomena in solid-state or condensed matter physics such as quantum phase transitions.

Quantum phase transition

The Innsbruck physicists have observed a "pinning transition" from a superfluid ("Luttinger liquid") to an insulated phase ("Mott-insulator"). In their experiment they showed that for strongly interacting atoms an additional weak lattice potential was sufficient to pin the atoms to fixed positions along the wire ("pinning"). The atoms were cooled down to nearly absolute zero and were in their quantum mechanical ground state. "It is not thermal fluctuations that induce the phase transition," stresses PhD student Elmar Haller, who is also first author of the study, which has been published in the journal Nature. "In fact, the atoms are already correlated due to strong repulsive interaction and only need a small push to align regularly along the optical lattice," explains Haller. When the lattice is removed, the atoms return to a superfluid state.

Theoretical prediction

The phenomenon observed by the experimental physicists was proposed by three theorists two years ago, two of whom -- Wilhelm Zwerger and Hans Peter Büchler -- also worked at the University of Innsbruck. This research work is funded by the Austrian Science Fund (FWF), the European Science Foundation (ESF) and by European Union research programs.

Ultracold Atoms (BEC)

Duplicate from physics.org

In the quest to reach colder and colder temperatures, physicists in 1995 created a remarkable new form of matter—neither gas, nor liquid, nor solid—called a Bose-Einstein condensate (BEC). First envisioned by Albert Einstein and a young Indian physicist named Satyendra Bose in the 1920s, BECs reveal properties of quantum mechanics—their atoms seem to merge together and lose their individual identity, behaving less like discrete particles and more like waves. If you're having trouble picturing this, not to worry; even physicists who work with BECs find them mind-boggling. In this interview, Luis Orozco of the University of Maryland, College Park offers some metaphors to help us begin to comprehend BECs and get a grasp of research in the strange world of ultracold atoms.

Suspended animation 

Q: What happens to the world when you get down to really low temperatures, and why is that of interest to you?

Luis Orozco: Probably the most important thing that low temperature brings us is that things move slowly, and as things start to move slower and slower you're able to look at them for extended periods of time. It is as if I were to ask you, "Could you tell me something about the handles of a car that is passing on a highway at 50 or 60 miles an hour?" Definitely you won't be able to say anything. But if the car is moving rather slowly, then you would be able to tell me, "Oh yes, the handle is this kind, that color, has these properties." Or: "There is no handle." And it's precisely that ability to interrogate the car—I am looking at the car for a long, long time—so I can get information out of it.

In the same sense, if we have cold atoms and they're moving very, very slowly, then I should be able to learn a lot and get information out of those atoms. I extend the time that they are available for me. Now, if I slow them enormously and I trap them, that would even be better, because now I have not just one path, but the atom will come back and will come back and will come back as if it were looking for a parking space in downtown Manhattan. So that atom is trapped going around and around. Now, many times we don't want to just work with one atom, we may want to have more and more atoms, but again it would be much better to have them moving slowly.

At room temperature an atom is moving at roughly 500 meters per second, so those are quite a few miles an hour (about 1,100 mph). However, if I slow it to a temperature that we can now achieve without much work in the lab, 200 microKelvin (about minus 460 F), then the atoms start to move about 20 centimeters per second (about 0.45 mph). Compared to something that's rushing in front of you, you'd be able to look at a lot of the details, a lot of the internal structure of that atom.

Now, why are we, in general, interested in that? Probably the first thing is because we want to have a better clock, and it is from the interrogation of that atom that we get the definition of the second. And by further cooling the atoms we have better clocks, and better clocks are giving us better global positioning systems, which are now a part of our daily life.

"Some people talk about the effects of BECs in things like neutron stars, where there could be really large condensates."

Q: What do we want to find out about atoms that we can't find out unless they're supercold?

Orozco: There are many things that we don't know about atoms, and one of those things in particular that I am interested in is the weak force. Imagine that you have to explain the weak force to your grandmother. Your grandmother remembers her high school chemistry, which says that the sun burns hydrogen and produces helium. But your grandma is very bright and says, "Yes, but if the sun only has hydrogen, how do you get helium out of that? Where did the neutron come from, because hydrogen doesn't have a neutron and helium has two?" And you say, "Hey, there is a weak force—that's how the sun starts its cycle, that's the key to how to convert a proton into a neutron. The weak force is, as its name says, very, very weak, and it has very few effects, but the most important effect is a striking one."

The weak force was predicted and found exactly 50 years ago, but we still have a lot to learn from it. It's a very, very small detail on the handle of the car, so we need to look at it for a very long time. We need to interrogate it very, very delicately. It is analogous to trying to measure the size of the Earth in its diameter and then changing it by a hair and then again finding what the diameter is. That's the rough scale.

So when we started this project to study the weak force, we definitely needed very, very slow atoms, and we not only needed slow atoms, we needed to confine them very carefully, put them in a trap so that we could interrogate, we could ask over and over and over the same question to eventually learn something about the weak interaction.

A quantum leap 

Q: In addition to slowing things down, what else can happen to atoms when you are in the realm of the ultracold?

Orozco: There is a second fascinating part that we haven't talked about and that is coherence. Coherence is that wonderful property that means things are correlated. A very good example is a soccer game. When you are in a soccer stadium, everybody is shouting all the time, and the noise level is pretty high. Then, what happens when there is a scoring goal? Every single person shouts "Goal!" at the same time, and there is this incredibly loud sound. Nobody is shouting louder than they were before, but they are shouting coherently. So by having the atoms ultracold, I can achieve much better coherence. When I ask the atoms in the right way, they will shout "Goal!" back to me in a very loud voice—that's the Bose-Einstein condensate (BEC).

Q: How many atoms can you get together with such coherence? In other words, is there a limit to how big a BEC can be?

Orozco: Well, I don't think there is a (theoretical) limit on how big a BEC can be. What limits us is more a matter of the "stadium" (the apparatus or environment in which the BEC is created). Some people talk about the effects of BECs in things like neutron stars, where there could be really large condensates, and of course we get some of their "Goal!" shouts by listening to pulsars and things like that. But in general, if you ask me right now what are the sizes that one can expect in the next few years for a BEC in a lab, I don't think we're going to get to a BEC of a gram; that's just too much.

Q: What's limiting the size of the stadium that physicists can build?

Orozco: There are various complications. The first complication, as you said, is really the size. As we make the stadium larger and larger, you have to control better and better the smoothness that you have in that environment. What is that smoothness? Well, that smoothness is the magnetic field. The environment has to be very, very well controlled.

There are other problems that can also happen. As I put more and more atoms in that stadium and I'm trying to cool them down, I'm trying to have them not move. I'm trying to also make them work coherently, but there are collisions. The individual people in the stadium are colliding with each other, and some are going to get upset and are going to leave. So that starts to happen at some point, and technically those bad collisions can limit you.

"We have to go to the ultracold, learn in the ultracold, and then bring that knowledge back into the room-temperature world."

Q: Are there other problems with working with a large stadium, to use your analogy?

Orozco: Imagine that you have an enormous stadium and the signal, the place where the goal is scored, is very far away. If you're a kilometer away, you're not going to see when they score. And so there is going to be a delay in your response, which is not good because that dilutes the coherence—the coherence is everybody jumping at the same time. So the speed of the propagation of the information across the space may be a problem.

I am sure that we are going to find ways to manage this. In many stadiums now they have big TV screens showing you what's going on. So probably we'll figure out a way to relay that information much faster to the other atoms, and then we'll be able to get larger and larger and larger condensates.

Potential applications 

Q: Given how difficult it appears to be to create a BEC, why are you so interested in it?

Orozco: Well, one of the dreams that is starting to become a reality is to use condensates in the context of quantum information. There are lots of ideas, lots of proposals, though nothing yet terribly concrete, where you would say, "Oh look, here is your quantum computer." However, we know it's a good idea because of coherence. The coherence is there, the atoms will work in a coherent way, and that's much, much better than each one individually doing it. So that's an important area that may have applications. I think it's worth pursuing, and many people are pursuing it.

Q: Speaking of practicalities, it seems perverse that you have to get down to these really low temperatures to achieve superconductivity, but to use superconductors, you really want them at room temperature ideally, don't you?

Orozco: We have had a lot of difficulty quantitatively understanding high-temperature superconductors (materials that conduct electricity with no resistance at temperatures above the boiling point of liquid nitrogen (77 K or minus 321 F)). We would like to have better high-temperature superconductors for a range of applications, from transferring electricity in a city, to medical applications, to transportation. So how are we going to do that?

Well, one of the things that we're learning about our ultracold world is that BECs are very simple systems and very good to manipulate. What we need to do is use the ultracold, use a BEC, and put that BEC in a lattice that has the same structure that a high-temperature superconductor can have. How would we make those lattices? We'd make those lattices with light. We'd force the atoms into a structure that is similar to the structure that the atoms have in the high-temperature superconductor. Then we can move and deform that pattern in such a way that we can see which patterns are better for superconductivity. Then we will be able to modify high-temperature superconductors to get much better applications. So to a certain extent we have to go to the ultracold, learn in the ultracold, and then bring that knowledge back into the room-temperature world. That would be wonderful.

Q: Going back to your car analogy, is it a bit like doing a 3-D computer design of a car that gives you the knowledge to physically build the thing? Are you trying to mimic that three-dimensional pattern that you've got in your BEC? Would you then try and actually build a similar pattern, a similar lattice in a solid crystal or something along those lines?

Orozco: Absolutely. The BEC gives me control. All the atoms are the same and I can create a pattern that is very uniform and has no defect. No defect is very difficult to get in the real world. However, if I have that beautiful control, then I can find out what are the necessary elements in that pattern. Where do I have to put the money to create a better high-temperature superconductor? Do I have to put more effort in having this particular pattern just where the oxygen is in the superconductor? Or do I have to look at where the rare air is? And so on. That is a fantastic tool. In your computer 3-D simulation of the car, are there defects? That's when you can test it. You understand all the laws of aerodynamics, all the laws of physics, and everything is tested in your computer. That is the role that the BEC can have for these other areas.

Interview conducted on January 9, 2007 by David Dugan, producer of "Absolute Zero," and edited by Lauren Aguirre, Executive Editor, and Susan K. Lewis, Editor, of NOVA online

Social Problem of Malaysian's Youngsters.

What a shameful phenomena occurs nowadays. Peoples are keep finger-pointing to put the blame on others. I suggest to stop talking and discussing and do the action immediately. No more theories of why is this happen but we need to focus on how to stop this from keep happening day by day.

From my point of view, all of us need to contribute and responsible to overcome this problem.

The suggestions:-

Government should:

1)blocks all porn's sites.

2)reduces useless entertainment activities and organize more benefit programmes to educate peoples of moral values, ethics, aqidah, tauhid, mentality and mind's setting.

3)No permittance to bussiness premis to operate more than 12.00am

4)NO more night club's and pub's

5)filter the dramas and films.

6)No advertisements for sexual products.

7)campaign for public awareness

8)jailed seized couples for syariah fault such as khalwat

9)serious punishment for those who abandoned their babies. Also punishment for those who have babies unmarried.

Parents and family should:

1)monitor your children's social life and behaviour.

2)build up and reinforce islamic education and train your family to live as a muslim (not western styles)

3)observe and monitor TV programmes and websites your children interested on.

4)get know their friends and dont let them out for free without telling where and why.

5)wears as a muslim (no tights, shorts etc)

Academic Institutions should:

1)monitor students' activity.

2)reduce entertainment programmes

3)strictly prevent students sit in couple.

4)block porn sites

Watching a Bose-Einstein condensate crystallize

Duplicate from Physics Today  http://blogs.physicstoday.org/update/2010/06/watching-a-bose-einstein-conde.html

In 1954 Princeton University’s Robert Dicke predicted a remarkable phenomenon: A dense cloud of excited atoms in a light field, he argued, could decay by spontaneously emitting coherent and highly polarized photons—an effect he termed superradiance.

By subtly altering the Hamiltonian, researchers in the early 1970s realized that the phenomenon need not be restricted to transient pulses, and they made their own prediction: When light and matter interact strongly enough, even at zero temperature, they can exhibit a steady-state superradiant phase. By confining a Bose–Einstein condensate of some 105 rubidium atoms driven by a standing-wave laser beam in an optical cavity, Tilman Esslinger and his colleagues at ETH Zürich have now observed the predicted quantum phase transition.

As shown in the sketch of their experiment, if the laser light exciting the BEC is intense enough to spawn superradiant photons along the cavity axis, the photons’ repeated reflections establish a field that interferes with the laser field to form a square-patterned potential. Because the condensate atoms produce the superradiant light, they are active participants, since atoms and photons dynamically influence each other’s motion through the coherent exchange of momentum. The upshot is that above some critical laser power, the atoms still exhibit superfluid behavior but become self-ordered into a crystalline lattice. Interestingly, although the Zürich group’s system is open, laser driven, and dissipative—far from the closed equilibrium system that Dicke considered—his Hamiltonian still captures the essential physics.

(K. Baumann et al., Nature 464, 1301, 2010.)—R. Mark Wilson