Generally speaking, a quant needs to be good at math (most important statistics, stochastics, calculus and algebra), programming (most important C++) and basic finance knowledge (Black-Scholes, Risk-neutral, options, futures, forward, bonds etc. ). Normally, a Ph.D. from physics, math, statistics, computer science or engineering (electrical engineering) of a top school, or a MBA in finance from a top school (This is rare), or a M.S. in financial engineering (if you come from this, you may already know a lot of this) can have no problem get interviews. If you are a Ph.D. from arts and social science, you will have a better shot converting to a consultant rather than a quant. But if you come from prestigeous school or you are super smart, it's not impossible.

    Nobody knows. Even you come from a prestigeous school, you may also fail the interviews and get nothing. If you don't have a strong background, you have to try harder, learn more finace, be better at math and practice your interview questions. If you have the luxuary, attend one of the financial engineering Master of Science programs offered across the country. It provides good return on your investment of money and time. Whatever, you have to try, Am I right?

• I am a Ph.D. in physics, mathematics, engineering, Should I/How can I convert to quant?

Many ways:
0. Attend your school's job fair and recruitment events. Large finance companies normally hold recruitment events at several prestige schools such as Harvard, Yale, Princeton, MIT etc. If you are the student of such schools, you have a higher possibility to get many interviews and as a result, you can easily become a quant easily.
1. Get a reference who is already in the field, ask him/her to submit your resume to his/her company, most people are ready to help others as they have had the similar experience as you. Plus, if you get hired, they normally get referral fee too, which is at least $5000 per person.
2. Contact a headhunter or recruiter, recruiters are old-hands from wall street, they have many conncections with the banks they previously worked for as well as acquaintences they met when they were working. Their acquaintences usually become senior persons or managers and they have the power to give you an interview. However, although recruiters are powful, you have to choose the right one to get you the right interviews. Some recruiters are simply collecting names to their database and boast to their clients (your future employers). There are some recruiters in our website. Go to our discussion forums for others' experience with recruiters.
3. Post your resume on career boards. This should be the first thing to do when you start searching job. Moster.com usually can get you lots of calls from recruiters. Tip: you should keep update your resume once a day to make it on the top of the list upon other candidates. Remember, there are thousands of people looking for the same job you are looking for. CareerBuilder.com is good too. I heard Yahoo! Hotjob is fine too, some students got some calls from recruiters. EfinanceCareer.com is specially for finance job, so you should definitely get into its database. You should also definitely look at our job board too.
4. The last way is much harder for most Ph.Ds. It requires highly professional skills in communication. It is to cold call the managers of the company you want to get into. You have to pass the gate-keepers all the way through a manager who can give you an interview. You can usually find their names and contact information on the company's website.

    What? you don't know programming as a Ph.D. You should learn at least one programming language, be it FORTRAN, C or C++. It's twenty-first centry already! If you really don't have any experience in programming, don't worry. You can learn it! Learn it like a language if you ever learn any foreign language. Any programming language has a set of keywords (like basic letters in English), some semantics (think about English again) and some special rules for you to write codes (think about writing in English you need put comma, separate paragraph, end a sentence). At the very first, you need remember the keywords, semantics. After you have learned some keywords, you can start program immediately. It will take you less than one month to get the basics of a programming language. You better learn C++ than other languages because it's most widely used in finance industry.

1. You will earn a lot but no more. Typical entry level for a quant PH.D. in a major bank on the street is about $100K plus bonus. The first year bonus is usually 50% of your base salary, it generally increases to 100% or more after the first year. So you should expect a total package of $300K per year after 3-5 years.
2. You will work a lot and more. A lot means 10-12 hours each day plus the travel time. It is normal for quants to come earlier and stay late. Sometimes without going home. If you don't like such life, do NOT jump!
3. It's highly volatile. Your job somehow depends largely on the goodness of the market. The market goes up, you earn more, the market goes down you earn less or even lose the job. People on wall street like to swing a lot.

Because the first quants are coming from physics, math. Everybody likes similar minds. They need you know mathematics well, able to program (hence the computer science). If you come from one of the fields, you have a much better chance of getting many interviews. You will know it when you start to send out resumes.